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[tor-commits] [tor-browser-spec/master] Add W3C-Identity Position Paper.
commit 832fc202564168747958e65458342f1a2919fcd6
Author: Mike Perry <mikeperry-git@xxxxxxxxxxxxxx>
Date: Thu Apr 30 14:58:50 2015 -0700
Add W3C-Identity Position Paper.
---
position-papers/W3C-Identity/W3CIdentity.bbl | 73 ++
position-papers/W3C-Identity/W3CIdentity.pdf | Bin 0 -> 74451 bytes
position-papers/W3C-Identity/W3CIdentity.tex | 373 ++++++++++
position-papers/W3C-Identity/llncs.cls | 1016 ++++++++++++++++++++++++++
position-papers/W3C-Identity/usenix.sty | 97 +++
5 files changed, 1559 insertions(+)
diff --git a/position-papers/W3C-Identity/W3CIdentity.bbl b/position-papers/W3C-Identity/W3CIdentity.bbl
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+\begin{thebibliography}{10}
+
+\bibitem{private-browsing}
+Gaurav Aggrawal, Elie Bursztein, Collin Jackson, and Dan Boneh.
+\newblock An analysis of private browsing modes in modern browsers.
+\newblock In {\em Proc. of 19th Usenix Security Symposium}, 2010.
+
+\bibitem{panopticlick}
+Peter Eckersley.
+\newblock How unique is your web browser?
+\newblock In {\em Proceedings of the 10th international conference on Privacy
+ enhancing technologies}, PETS'10, pages 1--18, Berlin, Heidelberg, 2010.
+ Springer-Verlag.
+
+\bibitem{safecache}
+Collin Jackson and Dan Boneh.
+\newblock Protecting browser state from web privacy attacks.
+\newblock In {\em In Proceedings of the International World Wide Web
+ Conference}, pages 737--744, 2006.
+
+\bibitem{security-fingerprinting}
+{Jennifer Valentino-DeVries}.
+\newblock {Evercookies and Fingerprinting: Are Anti-Fraud Tools Good for Ads?},
+ 2010.
+\newblock
+ \url{http://blogs.wsj.com/digits/2010/12/01/evercookies-and-fingerprinting-f%
+inding-fraudsters-tracking-consumers/}.
+
+\bibitem{wsj-fingerprinting}
+{Julia Angwin and Jennifer Valentino-DeVries}.
+\newblock {Race Is On to 'Fingerprint' Phones, PCs}, 2010.
+\newblock
+ \url{http://online.wsj.com/article/SB100014240527487046792045756467041009595%
+46.html}.
+
+\bibitem{firefox-personas}
+Mozilla.
+\newblock Personas.
+\newblock \url{https://mozillalabs.com/personas/}.
+
+\bibitem{weave-manager}
+Mozilla.
+\newblock {The Weave Account Manager}.
+\newblock \url{https://wiki.mozilla.org/Labs/Weave/Identity/Account_Manager}.
+
+\bibitem{not-to-toggle}
+Mike Perry.
+\newblock To toggle, or not to toggle: The end of torbutton.
+\newblock
+ \url{https://lists.torproject.org/pipermail/tor-talk/2011-April/020077.html}.
+
+\bibitem{torbutton}
+Mike Perry.
+\newblock {The Torbutton Design Document}, 2011.
+\newblock \url{https://www.torproject.org/torbutton/en/design/}.
+
+\bibitem{facebook-like}
+Arnold Roosendaal.
+\newblock {Facebook Tracks and Traces Everyone: Like This!}
+\newblock {\em SSRN eLibrary}, 2010.
+
+\bibitem{tracking-identity}
+Emily Steel.
+\newblock {Online Tracking Company RapLeaf Profiles Users By Name}, 2010.
+\newblock
+ \url{http://online.wsj.com/article/SB100014240527023044105045755602432594160%
+72.html}.
+
+\bibitem{thirdparty}
+Dan Witte.
+\newblock \url{https://wiki.mozilla.org/Thirdparty}.
+
+\end{thebibliography}
diff --git a/position-papers/W3C-Identity/W3CIdentity.pdf b/position-papers/W3C-Identity/W3CIdentity.pdf
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diff --git a/position-papers/W3C-Identity/W3CIdentity.tex b/position-papers/W3C-Identity/W3CIdentity.tex
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+%\documentclass{llncs}
+\documentclass[letterpaper,11pt]{llncs}
+%\documentclass{article} % llncs
+
+\usepackage{usenix}
+\usepackage{url}
+\usepackage{amsmath}
+\usepackage{epsfig}
+\usepackage{epsf}
+\usepackage{listings}
+
+%\setlength{\textwidth}{6in}
+%\setlength{\textheight}{8.4in}
+%\setlength{\topmargin}{.5cm}
+%\setlength{\oddsidemargin}{1cm}
+%\setlength{\evensidemargin}{1cm}
+
+\begin{document}
+
+\title{Bridging the Disconnect Between Web Identity and User Perception}
+
+\author{Mike Perry \\ The Internet \\ mikeperry@xxxxxxxxxxxxxx}
+
+%\institute{The Internet}
+
+\maketitle
+\pagestyle{plain}
+
+\begin{abstract}
+
+There is a huge disconnect between how users perceive their online presence
+and the reality of their relationship with the websites they visit. This
+position paper explores this disconnect and provides some recommendations for
+making the technical reality of the web match user perception, through both
+technical improvements as well as user interface cues. By looking at all of
+the elements of tracking as though they collectively comprise "User Identity",
+we can make better decisions about improvements to both the technical and the
+interface aspects of authentication and privacy.
+
+\end{abstract}
+
+\section{Introduction}
+
+The prevailing revenue model of the web is an appealing one. Web users receive
+unfettered, frictionless access to an extensive variety of information sources
+in exchange for viewing advertising. This advertising is more valuable if each
+advertisement is more relevant to the current activity, and if possible, more
+relevant to the current user.
+
+The cost of this is that user privacy on the web is a nightmare. There is
+ubiquitous tracking, unseen partnership agreements and data exchange, and
+surreptitious attempts to uncover users' identities against their will and
+without their knowledge. This is not just happening in the dark, unseemly
+corners of the web. It is happening everywhere\cite{facebook-like}.
+
+The problem is that the revenue model of the web has incentivized companies to
+find ways to continue to track users against their will, even if those users
+are attempting to protect themselves through currently available methods.
+Starting with the infamous "Flash cookies", we have progressed through a
+seemingly endless arms race of secondary identifiers and tracking information:
+visited history, cache, font and system data, desktop resolution, keystroke
+timing, and so on and so forth\cite{wsj-fingerprinting}.
+
+These efforts have lead to an even wider disconnect between a user's
+perception of their privacy and the reality of their privacy. Users simply
+can't keep up with the ways they are being tracked.
+
+When users are being coerced into ceding data about themselves without clear
+understanding or consent (and in fact, in many cases despite their explicit
+attempts to decline to consent), serious moral issues begin to arise.
+
+To understand and evaluate potential solutions and improvements to this status
+quo, we must explore the disconnect between user experience and the way the
+web actually functions with respect to tracking and identity.
+
+% FIXME: Do we need this paragraph?
+%To this end, the rest of this document is structured as follows: First, we
+%examine user identity on the web, comparing the average user's perspective to
+%what actually is happening technically behind the scenes, and noting the major
+%disconnects. We then examine solutions attempting to bridge this disconnect
+%from two different directions.
+
+We only consider implementations that involve privacy-by-design.
+Privacy-by-policy approaches such as Do Not Track will not be discussed.
+
+\section{User Identity on the Web}
+
+To properly examine this privacy problem, we must probe into the details of
+both what a User's perception of their identity is, as well as the technical
+realities of what goes into web authentication and tracking.
+
+\subsection{User Perception of Identity}
+
+Instinctively, users define their privacy in terms of their identity, in terms
+of how they have interacted with a site in order to inform it of who they are.
+Typically, the user's perception of their identity on the web is usually a direct
+function of the mechanisms used for strong authentication for particular sites.
+
+For example, users expect that logging in to Facebook creates a relationship
+in their browsers when facebook.com is present in the URL bar, but they are
+likely not aware that this also extends to their activity on other, arbitrary
+sites that happen to include "Like this on Facebook" buttons or
+Facebook-sourced advertising content.
+
+Many, if not most, users expect that when they log out of a site their
+relationship ends and that any associated tracking should be over. Even
+users who are aware of cookies can be prone to believing that clearing the
+cookies and private browsing data related to a particular site is sufficient
+to end their relationship with that site.
+
+Neither of these beliefs has any relation to reality.
+
+\subsection{Technical Reality of Identity}
+
+The technical reality of the web today is that users are usually wrong about
+their authentication status with respect to a particular site, and are almost
+always oblivious to the relationship between content elements of arbitrary
+pages. The default experience is such that all of this data exchange is
+concealed from the user.
+
+So then what is identity? In terms of authentication, it would at first appear
+to be cookies, HTTP Auth tokens, and client TLS certificates. However, even this
+begins to break down. High-security websites are already using fingerprinting
+as an auxiliary second factor of authentication\cite{security-fingerprinting},
+and online data aggregators utilize everything they can to build complete
+portraits of users' identities\cite{tracking-identity}.
+
+Identity then is a superset of all the authentication tokens used by the
+browser. It is the ability to link a user's activity in one instance to their
+activity in another instance, be it across time, or even on a single page
+due to multiple content origins.
+
+\subsection{Identity as Linkability}
+
+When expanded to cover all items that enable or substantially contribute to
+Linkability, a lot more components of the browser are now in scope. We will
+briefly enumerate these components.
+
+First, the obvious properties are found in the state of the browser: cookies,
+DOM storage, cache, cryptographic tokens and cryptographic state, and
+location. These are what technical people tend to think of first when it comes
+to private browsing and identity, but they are not the whole story.
+
+Next, we have long-term properties of the browser itself. These include the
+User Agent String, the list of installed plugins, rendering capabilities,
+window decoration size, and browser widget size.
+
+Then, we have properties of the computer. These include desktop size, IP
+address, clock offset and timezone, and installed fonts.
+
+Finally, linkability also includes the properties of the multi-origin model of
+the web that allow tracking due to partnerships. These include the implicit
+cookie transmission model, and also explicit click referral and data exchange
+partnerships.
+
+\subsection{Developing a Threat Model}
+
+Unfortunately, just about every browser property and functionality is a
+potential fingerprinting target. In order to properly address the network
+adversary on a technical level, we need a metric to measure linkability of the
+various browser properties that extend beyond any stored origin-related state.
+
+The Panopticlick project by the EFF provides us with exactly this
+metric\cite{panopticlick}. The researchers conducted a survey of volunteers
+who were asked to visit an experiment page that harvested many of the above
+components. They then computed the Shannon Entropy of the resulting
+distribution of each of several key attributes to determine how many bits of
+identifying information each attribute provided.
+
+While not perfect\footnotemark, this metric allows us to prioritize effort at
+components that have the most potential for linkability.
+
+\footnotetext{In particular, the test does not take in all aspects of
+resolution information. It did not calculate the size of widgets, window
+decoration, or toolbar size. We believe this may add high amounts of entropy
+to the screen field. It also did not measure clock offset and other time-based
+fingerprints. Furthermore, as new browser features are added, this experiment
+should be repeated to include them.}
+
+This metric also indicates that it is beneficial to standardize on
+implementations of fingerprinting resistance where possible. More
+implementations using the same defenses means more users with similar
+fingerprints, which means less entropy in the metric.
+
+\section{Matching User Perception with Reality}
+
+When the concept of user identity is expanded to cover all aspects of
+linkability, addressing the problem of the disconnect between user perception
+and reality becomes clearer. For users to have privacy, and for private
+browsing modes to function, the relationship between a user and a site must be
+understood by that user.
+
+It is apparent that the user experiences disconnect with the technical
+realities of the web on two major fronts: the average user does not grasp the
+privacy implications of the multi-origin model, nor are they given a clear
+concept of identity to grasp the privacy implications of the union of the
+trackable components of their browsers.
+
+We will now examine examples of attempts at reducing this disconnect on each
+of these two fronts.
+
+Note that identity-based approaches and the origin-based approaches are
+orthogonal. They may be combined, or used independently.
+
+\subsection{Origin-Based Approaches}
+
+Origin-based approaches seek to improve the technical behavior of the browser
+to make linkability less implicit and more consent-driven. In short, these
+approaches seek to make the web behave more like users currently assume it
+behaves by anchoring browser state to top-level origins as opposed to
+associating it with arbitrary content elements.
+
+The earliest relevant example of this work is SafeCache\cite{safecache}.
+SafeCache seeks to reduce the ability for 3rd party content elements to use
+the cache to store identifiers. It does this by limiting the scope of the
+cache to the origin in the url bar. This has the effect that commonly sourced
+content elements are fetched and cached repeatedly, but this is the desired
+property. Each of these prevalent content elements can be crafted to include
+unique identifiers for each user, tracking users who attempt to avoid tracking
+by clearing cookies.
+
+Mozilla has a wonderful example of an origin-based improvement written by Dan
+Witte and buried on their wiki\cite{thirdparty}. It describes a new dual-keyed
+origin for cookies, so that cookies would only be transmitted if they matched
+both the top level origin and the third party origin involved in their
+creation. This approach would go a long way towards preventing implicit
+tracking across multiple websites.
+
+Similarly, one could imagine this two-level origin isolation being deployed to
+improve similar issues with DOM Storage and cryptographic tokens.
+
+Making the origin model for browser identifiers more closely match the user
+activity and user expectation has other advantages as well. With a clear
+distinction between 3rd party and top-level cookies, the privacy settings
+window could have a user-intuitive way of representing the user's relationship
+with different origins, perhaps by using only the favicon of that top level
+origin to represent all of the browser state accumulated by that origin. The
+user could delete the entire set of browser state (cookies, cache, storage,
+cryptographic tokens) associated with a site simply by removing its favicon
+from their privacy info panel.
+
+The problem with origin-based approaches is that individually, they do not
+fully address the entire linkability problem unless the same restriction is
+applied uniformly to all aspects of stored browser state, and all other
+linkability issues are dealt with. Behind-the-scenes partnerships can easily
+allow companies to continue to link users to their identities through any
+aspect of browser state that is not properly compartmentalized to the top
+level origin and bound to the same rules.
+
+% FIXME: Wording..
+However, linkability based on browser properties is amenable to this
+model. In particular, one can imagine per-origin plugin permissions,
+per-origin limits on the number of fonts that can be used, and randomized
+window-specific time offsets.
+
+So, while these approaches are in fact useful for bringing the technical
+realities of the web closer to what the user assumes is happening, they must
+be deployed uniformly, with a consistent top-level origin restriction model.
+This may take significant coordination and standardization efforts.
+
+\subsection{Identity-Based Approaches}
+
+We will now discuss what we call the identity-based approaches to privacy.
+These approaches, whether explicitly or implicitly, all model the user's web
+identity as the entirety of the user's state for all origins.
+
+The key advantage of identity-based approaches is that they can be simpler
+than origin-based approaches when used to improve the privacy problem on their
+own.
+
+While the earliest example of an identity-based approach is our own work on
+Torbutton\cite{torbutton}, Torbutton deserves poor marks for both simplicity
+and usability\cite{not-to-toggle}. Torbutton attempts to isolate the user's
+non-Tor activity from their Tor activity, effectively providing the user with
+a blank slate for their Tor activity, but optionally allowing them to toggle
+between these two identities.
+
+Firefox Private Browsing Mode is similar, in that it allows users to switch
+between their normal browsing and a "private" clean slate.
+
+% FIXME: This paragraph can go if we need space:
+Both Firefox PBM and Torbutton suffer from usability issues, primarily because
+this concept of separate browsing identities is not properly conveyed to the
+user. In Firefox's case, this usability issue is apparent through the quantity
+of mode error observed in the review of Private Browsing Modes by Dan Boneh et
+al\cite{private-browsing}. In Torbutton's case, the issues appear more severe.
+We've informally observed that users have tremendous difficulties remembering
+which tabs were Tor-related and which were non-Tor related, and we've also
+observed issues with mode error.
+
+Both of these approaches are exceedingly complex: they deal with every aspect
+of browser state individually. This development effort however does enable
+Firefox and Torbutton to provide the user with great fine-grained control.
+
+Google Chrome's Incognito Mode comes the closest to conveying this idea of
+"Incognito identity" to the user, and the implementation is also simpler as a
+result. The Incognito Mode window is a separate, stylized window that clearly
+conveys an alternate identity is in use for this window, which can be used
+concurrent to the non-private identity. This appears to lead to less mode
+error (where the user forgets their private browsing state) compared to other
+browsers.
+
+% FIXME: This paragraph can go if we need space:
+The implementation of Incognito is as a virtualized in-memory profile, which
+allows them to achieve protection against history storage issues with minimal
+effort. It also allows them to tweak browser properties and permissions
+specifically for this profile.
+
+The Mozilla Weave project appears to be proposing an identity-based method of
+managing, syncing, and storing authentication tokens, and also has use cases
+described for multiple users of a single browser\cite{weave-manager}. It is
+the closest idea on paper to what we envision as the way to bridge user
+assumptions with reality.
+
+We believe that the user interface of the browser should convey a sense of
+persistent identity prominently to the user in the form of a visual cue. This
+cue can either be an abstract image, graphic or theme (such as the user's
+choice of Firefox Persona\cite{firefox-personas}), or it can be a text area
+with the user's current favored pseudonym. This idea of identity should then
+be integrated with the browsing experience. Users should be able to click a
+button to get a clean slate for a new identity, and should be able to log in
+and out of of password-protected stored encrypted identities, which would
+contain the entire state of the browser. This is the direction the Tor Project
+intends to head in with the Tor Browser Bundle\cite{not-to-toggle}.
+
+To this user, the Private Browsing Mode would be no more than a special case
+of this identity UI - a special identity that they can trust not to store
+browsing history information to disk. Such a UI also more explicitly captures
+what is going on with respect to the user's relationship to the web.
+
+However, all current private browsing modes fall short of protecting against a
+network adversary and fail to deal with linkability against a network
+adversary\cite{private-browsing}, claiming that it is outside their threat
+model\footnotemark. If the user is given a new identity that is still linkable
+to the previous one due to shortcomings of the browser, this approach has
+failed as a privacy measure.
+
+\footnotetext{The primary reason given to abstain from addressing the network
+adversary is IP address linkability. However, we believe this to be a red
+herring. Users are quite capable of using alternate Internet connections, and
+it is common practice for ISPs in many parts of the world to rotate user IP
+addresses daily, to discourage servers and to impede the spread of malware.
+This is especially true of cellular IP networks.}
+
+Linkability solutions within the identity framework would be similar to the
+origin-based solutions, except they would be properties of the entire browser
+or browser profile, and would be obfuscated only once per identity switch.
+
+% FIXME: Elaborate?
+
+\section{Conclusions}
+
+There is a demand for private browsing, and we believe that solid private
+browsing modes can be created. In order to do this, we need solid analysis of
+the threat models involved, and we need standardization for many aspects of
+defense.
+
+However, there is currently a huge disconnect between user privacy and
+identity due to both the multi-origin nature of the web, and the failure of
+browsers to adequately convey a sense of identity to the user. It is possible
+to bridge this disconnect both by addressing the issues with the multi-origin
+model, as well as providing the user with an explicit representation of their
+web identity, and with control over this identity.
+
+% XXX: The dangers of adblockers and filters + the long-term imperative of
+% improving privacy for the continued use of the advertising revenue model.
+
+\bibliographystyle{plain} \bibliography{W3CIdentity}
+
+\clearpage
+\appendix
+
+\end{document}
diff --git a/position-papers/W3C-Identity/llncs.cls b/position-papers/W3C-Identity/llncs.cls
new file mode 100644
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--- /dev/null
+++ b/position-papers/W3C-Identity/llncs.cls
@@ -0,0 +1,1016 @@
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+ \Large \bfseries #1\par\nobreak
+ \vskip 40\p@
+ }}
+\def\@schapter#1{\if@twocolumn
+ \@topnewpage[\@makeschapterhead{#1}]%
+ \else
+ \@makeschapterhead{#1}%
+ \@afterheading
+ \fi}
+\def\@makeschapterhead#1{%
+% \vspace*{50\p@}%
+ {\centering
+ \normalfont
+ \interlinepenalty\@M
+ \Large \bfseries #1\par\nobreak
+ \vskip 40\p@
+ }}
+
+\renewcommand\section{\@startsection{section}{1}{\z@}%
+ {-18\p@ \@plus -4\p@ \@minus -4\p@}%
+ {12\p@ \@plus 4\p@ \@minus 4\p@}%
+ {\normalfont\large\bfseries\boldmath
+ \rightskip=\z@ \@plus 8em\pretolerance=10000 }}
+\renewcommand\subsection{\@startsection{subsection}{2}{\z@}%
+ {-18\p@ \@plus -4\p@ \@minus -4\p@}%
+ {8\p@ \@plus 4\p@ \@minus 4\p@}%
+ {\normalfont\normalsize\bfseries\boldmath
+ \rightskip=\z@ \@plus 8em\pretolerance=10000 }}
+\renewcommand\subsubsection{\@startsection{subsubsection}{3}{\z@}%
+ {-18\p@ \@plus -4\p@ \@minus -4\p@}%
+ {-0.5em \@plus -0.22em \@minus -0.1em}%
+ {\normalfont\normalsize\bfseries\boldmath}}
+\renewcommand\paragraph{\@startsection{paragraph}{4}{\z@}%
+ {-12\p@ \@plus -4\p@ \@minus -4\p@}%
+ {-0.5em \@plus -0.22em \@minus -0.1em}%
+ {\normalfont\normalsize\itshape}}
+\renewcommand\subparagraph[1]{\typeout{LLNCS warning: You should not use
+ \string\subparagraph\space with this class}\vskip0.5cm
+You should not use \verb|\subparagraph| with this class.\vskip0.5cm}
+
+\DeclareMathSymbol{\Gamma}{\mathalpha}{letters}{"00}
+\DeclareMathSymbol{\Delta}{\mathalpha}{letters}{"01}
+\DeclareMathSymbol{\Theta}{\mathalpha}{letters}{"02}
+\DeclareMathSymbol{\Lambda}{\mathalpha}{letters}{"03}
+\DeclareMathSymbol{\Xi}{\mathalpha}{letters}{"04}
+\DeclareMathSymbol{\Pi}{\mathalpha}{letters}{"05}
+\DeclareMathSymbol{\Sigma}{\mathalpha}{letters}{"06}
+\DeclareMathSymbol{\Upsilon}{\mathalpha}{letters}{"07}
+\DeclareMathSymbol{\Phi}{\mathalpha}{letters}{"08}
+\DeclareMathSymbol{\Psi}{\mathalpha}{letters}{"09}
+\DeclareMathSymbol{\Omega}{\mathalpha}{letters}{"0A}
+
+\let\footnotesize\small
+
+\if@custvec
+\def\vec#1{\mathchoice{\mbox{\boldmath$\displaystyle#1$}}
+{\mbox{\boldmath$\textstyle#1$}}
+{\mbox{\boldmath$\scriptstyle#1$}}
+{\mbox{\boldmath$\scriptscriptstyle#1$}}}
+\fi
+
+\def\squareforqed{\hbox{\rlap{$\sqcap$}$\sqcup$}}
+\def\qed{\ifmmode\squareforqed\else{\unskip\nobreak\hfil
+\penalty50\hskip1em\null\nobreak\hfil\squareforqed
+\parfillskip=0pt\finalhyphendemerits=0\endgraf}\fi}
+
+\def\getsto{\mathrel{\mathchoice {\vcenter{\offinterlineskip
+\halign{\hfil
+$\displaystyle##$\hfil\cr\gets\cr\to\cr}}}
+{\vcenter{\offinterlineskip\halign{\hfil$\textstyle##$\hfil\cr\gets
+\cr\to\cr}}}
+{\vcenter{\offinterlineskip\halign{\hfil$\scriptstyle##$\hfil\cr\gets
+\cr\to\cr}}}
+{\vcenter{\offinterlineskip\halign{\hfil$\scriptscriptstyle##$\hfil\cr
+\gets\cr\to\cr}}}}}
+\def\lid{\mathrel{\mathchoice {\vcenter{\offinterlineskip\halign{\hfil
+$\displaystyle##$\hfil\cr<\cr\noalign{\vskip1.2pt}=\cr}}}
+{\vcenter{\offinterlineskip\halign{\hfil$\textstyle##$\hfil\cr<\cr
+\noalign{\vskip1.2pt}=\cr}}}
+{\vcenter{\offinterlineskip\halign{\hfil$\scriptstyle##$\hfil\cr<\cr
+\noalign{\vskip1pt}=\cr}}}
+{\vcenter{\offinterlineskip\halign{\hfil$\scriptscriptstyle##$\hfil\cr
+<\cr
+\noalign{\vskip0.9pt}=\cr}}}}}
+\def\gid{\mathrel{\mathchoice {\vcenter{\offinterlineskip\halign{\hfil
+$\displaystyle##$\hfil\cr>\cr\noalign{\vskip1.2pt}=\cr}}}
+{\vcenter{\offinterlineskip\halign{\hfil$\textstyle##$\hfil\cr>\cr
+\noalign{\vskip1.2pt}=\cr}}}
+{\vcenter{\offinterlineskip\halign{\hfil$\scriptstyle##$\hfil\cr>\cr
+\noalign{\vskip1pt}=\cr}}}
+{\vcenter{\offinterlineskip\halign{\hfil$\scriptscriptstyle##$\hfil\cr
+>\cr
+\noalign{\vskip0.9pt}=\cr}}}}}
+\def\grole{\mathrel{\mathchoice {\vcenter{\offinterlineskip
+\halign{\hfil
+$\displaystyle##$\hfil\cr>\cr\noalign{\vskip-1pt}<\cr}}}
+{\vcenter{\offinterlineskip\halign{\hfil$\textstyle##$\hfil\cr
+>\cr\noalign{\vskip-1pt}<\cr}}}
+{\vcenter{\offinterlineskip\halign{\hfil$\scriptstyle##$\hfil\cr
+>\cr\noalign{\vskip-0.8pt}<\cr}}}
+{\vcenter{\offinterlineskip\halign{\hfil$\scriptscriptstyle##$\hfil\cr
+>\cr\noalign{\vskip-0.3pt}<\cr}}}}}
+\def\bbbr{{\rm I\!R}} %reelle Zahlen
+\def\bbbm{{\rm I\!M}}
+\def\bbbn{{\rm I\!N}} %natuerliche Zahlen
+\def\bbbf{{\rm I\!F}}
+\def\bbbh{{\rm I\!H}}
+\def\bbbk{{\rm I\!K}}
+\def\bbbp{{\rm I\!P}}
+\def\bbbone{{\mathchoice {\rm 1\mskip-4mu l} {\rm 1\mskip-4mu l}
+{\rm 1\mskip-4.5mu l} {\rm 1\mskip-5mu l}}}
+\def\bbbc{{\mathchoice {\setbox0=\hbox{$\displaystyle\rm C$}\hbox{\hbox
+to0pt{\kern0.4\wd0\vrule height0.9\ht0\hss}\box0}}
+{\setbox0=\hbox{$\textstyle\rm C$}\hbox{\hbox
+to0pt{\kern0.4\wd0\vrule height0.9\ht0\hss}\box0}}
+{\setbox0=\hbox{$\scriptstyle\rm C$}\hbox{\hbox
+to0pt{\kern0.4\wd0\vrule height0.9\ht0\hss}\box0}}
+{\setbox0=\hbox{$\scriptscriptstyle\rm C$}\hbox{\hbox
+to0pt{\kern0.4\wd0\vrule height0.9\ht0\hss}\box0}}}}
+\def\bbbq{{\mathchoice {\setbox0=\hbox{$\displaystyle\rm
+Q$}\hbox{\raise
+0.15\ht0\hbox to0pt{\kern0.4\wd0\vrule height0.8\ht0\hss}\box0}}
+{\setbox0=\hbox{$\textstyle\rm Q$}\hbox{\raise
+0.15\ht0\hbox to0pt{\kern0.4\wd0\vrule height0.8\ht0\hss}\box0}}
+{\setbox0=\hbox{$\scriptstyle\rm Q$}\hbox{\raise
+0.15\ht0\hbox to0pt{\kern0.4\wd0\vrule height0.7\ht0\hss}\box0}}
+{\setbox0=\hbox{$\scriptscriptstyle\rm Q$}\hbox{\raise
+0.15\ht0\hbox to0pt{\kern0.4\wd0\vrule height0.7\ht0\hss}\box0}}}}
+\def\bbbt{{\mathchoice {\setbox0=\hbox{$\displaystyle\rm
+T$}\hbox{\hbox to0pt{\kern0.3\wd0\vrule height0.9\ht0\hss}\box0}}
+{\setbox0=\hbox{$\textstyle\rm T$}\hbox{\hbox
+to0pt{\kern0.3\wd0\vrule height0.9\ht0\hss}\box0}}
+{\setbox0=\hbox{$\scriptstyle\rm T$}\hbox{\hbox
+to0pt{\kern0.3\wd0\vrule height0.9\ht0\hss}\box0}}
+{\setbox0=\hbox{$\scriptscriptstyle\rm T$}\hbox{\hbox
+to0pt{\kern0.3\wd0\vrule height0.9\ht0\hss}\box0}}}}
+\def\bbbs{{\mathchoice
+{\setbox0=\hbox{$\displaystyle \rm S$}\hbox{\raise0.5\ht0\hbox
+to0pt{\kern0.35\wd0\vrule height0.45\ht0\hss}\hbox
+to0pt{\kern0.55\wd0\vrule height0.5\ht0\hss}\box0}}
+{\setbox0=\hbox{$\textstyle \rm S$}\hbox{\raise0.5\ht0\hbox
+to0pt{\kern0.35\wd0\vrule height0.45\ht0\hss}\hbox
+to0pt{\kern0.55\wd0\vrule height0.5\ht0\hss}\box0}}
+{\setbox0=\hbox{$\scriptstyle \rm S$}\hbox{\raise0.5\ht0\hbox
+to0pt{\kern0.35\wd0\vrule height0.45\ht0\hss}\raise0.05\ht0\hbox
+to0pt{\kern0.5\wd0\vrule height0.45\ht0\hss}\box0}}
+{\setbox0=\hbox{$\scriptscriptstyle\rm S$}\hbox{\raise0.5\ht0\hbox
+to0pt{\kern0.4\wd0\vrule height0.45\ht0\hss}\raise0.05\ht0\hbox
+to0pt{\kern0.55\wd0\vrule height0.45\ht0\hss}\box0}}}}
+\def\bbbz{{\mathchoice {\hbox{$\mathsf\textstyle Z\kern-0.4em Z$}}
+{\hbox{$\mathsf\textstyle Z\kern-0.4em Z$}}
+{\hbox{$\mathsf\scriptstyle Z\kern-0.3em Z$}}
+{\hbox{$\mathsf\scriptscriptstyle Z\kern-0.2em Z$}}}}
+
+\let\ts\,
+
+\setlength\leftmargini {17\p@}
+\setlength\leftmargin {\leftmargini}
+\setlength\leftmarginii {\leftmargini}
+\setlength\leftmarginiii {\leftmargini}
+\setlength\leftmarginiv {\leftmargini}
+\setlength \labelsep {.5em}
+\setlength \labelwidth{\leftmargini}
+\addtolength\labelwidth{-\labelsep}
+
+\def\@listI{\leftmargin\leftmargini
+ \parsep 0\p@ \@plus1\p@ \@minus\p@
+ \topsep 8\p@ \@plus2\p@ \@minus4\p@
+ \itemsep0\p@}
+\let\@listi\@listI
+\@listi
+\def\@listii {\leftmargin\leftmarginii
+ \labelwidth\leftmarginii
+ \advance\labelwidth-\labelsep
+ \topsep 0\p@ \@plus2\p@ \@minus\p@}
+\def\@listiii{\leftmargin\leftmarginiii
+ \labelwidth\leftmarginiii
+ \advance\labelwidth-\labelsep
+ \topsep 0\p@ \@plus\p@\@minus\p@
+ \parsep \z@
+ \partopsep \p@ \@plus\z@ \@minus\p@}
+
+\renewcommand\labelitemi{\normalfont\bfseries --}
+\renewcommand\labelitemii{$\m@th\bullet$}
+
+\setlength\arraycolsep{1.4\p@}
+\setlength\tabcolsep{1.4\p@}
+
+\def\tableofcontents{\chapter*{\contentsname\@mkboth{{\contentsname}}%
+ {{\contentsname}}}
+ \def\authcount##1{\setcounter{auco}{##1}\setcounter{@auth}{1}}
+ \def\lastand{\ifnum\value{auco}=2\relax
+ \unskip{} \andname\
+ \else
+ \unskip \lastandname\
+ \fi}%
+ \def\and{\stepcounter{@auth}\relax
+ \ifnum\value{@auth}=\value{auco}%
+ \lastand
+ \else
+ \unskip,
+ \fi}%
+ \@starttoc{toc}\if@restonecol\twocolumn\fi}
+
+\def\l@part#1#2{\addpenalty{\@secpenalty}%
+ \addvspace{2em plus\p@}% % space above part line
+ \begingroup
+ \parindent \z@
+ \rightskip \z@ plus 5em
+ \hrule\vskip5pt
+ \large % same size as for a contribution heading
+ \bfseries\boldmath % set line in boldface
+ \leavevmode % TeX command to enter horizontal mode.
+ #1\par
+ \vskip5pt
+ \hrule
+ \vskip1pt
+ \nobreak % Never break after part entry
+ \endgroup}
+
+\def\@dotsep{2}
+
+\def\hyperhrefextend{\ifx\hyper@anchor\@undefined\else
+{chapter.\thechapter}\fi}
+
+\def\addnumcontentsmark#1#2#3{%
+\addtocontents{#1}{\protect\contentsline{#2}{\protect\numberline
+ {\thechapter}#3}{\thepage}\hyperhrefextend}}
+\def\addcontentsmark#1#2#3{%
+\addtocontents{#1}{\protect\contentsline{#2}{#3}{\thepage}\hyperhrefextend}}
+\def\addcontentsmarkwop#1#2#3{%
+\addtocontents{#1}{\protect\contentsline{#2}{#3}{0}\hyperhrefextend}}
+
+\def\@adcmk[#1]{\ifcase #1 \or
+\def\@gtempa{\addnumcontentsmark}%
+ \or \def\@gtempa{\addcontentsmark}%
+ \or \def\@gtempa{\addcontentsmarkwop}%
+ \fi\@gtempa{toc}{chapter}}
+\def\addtocmark{\@ifnextchar[{\@adcmk}{\@adcmk[3]}}
+
+\def\l@chapter#1#2{\addpenalty{-\@highpenalty}
+ \vskip 1.0em plus 1pt \@tempdima 1.5em \begingroup
+ \parindent \z@ \rightskip \@pnumwidth
+ \parfillskip -\@pnumwidth
+ \leavevmode \advance\leftskip\@tempdima \hskip -\leftskip
+ {\large\bfseries\boldmath#1}\ifx0#2\hfil\null
+ \else
+ \nobreak
+ \leaders\hbox{$\m@th \mkern \@dotsep mu.\mkern
+ \@dotsep mu$}\hfill
+ \nobreak\hbox to\@pnumwidth{\hss #2}%
+ \fi\par
+ \penalty\@highpenalty \endgroup}
+
+\def\l@title#1#2{\addpenalty{-\@highpenalty}
+ \addvspace{8pt plus 1pt}
+ \@tempdima \z@
+ \begingroup
+ \parindent \z@ \rightskip \@tocrmarg
+ \parfillskip -\@tocrmarg
+ \leavevmode \advance\leftskip\@tempdima \hskip -\leftskip
+ #1\nobreak
+ \leaders\hbox{$\m@th \mkern \@dotsep mu.\mkern
+ \@dotsep mu$}\hfill
+ \nobreak\hbox to\@pnumwidth{\hss #2}\par
+ \penalty\@highpenalty \endgroup}
+
+\setcounter{tocdepth}{0}
+\newdimen\tocchpnum
+\newdimen\tocsecnum
+\newdimen\tocsectotal
+\newdimen\tocsubsecnum
+\newdimen\tocsubsectotal
+\newdimen\tocsubsubsecnum
+\newdimen\tocsubsubsectotal
+\newdimen\tocparanum
+\newdimen\tocparatotal
+\newdimen\tocsubparanum
+\tocchpnum=\z@ % no chapter numbers
+\tocsecnum=15\p@ % section 88. plus 2.222pt
+\tocsubsecnum=23\p@ % subsection 88.8 plus 2.222pt
+\tocsubsubsecnum=27\p@ % subsubsection 88.8.8 plus 1.444pt
+\tocparanum=35\p@ % paragraph 88.8.8.8 plus 1.666pt
+\tocsubparanum=43\p@ % subparagraph 88.8.8.8.8 plus 1.888pt
+\def\calctocindent{%
+\tocsectotal=\tocchpnum
+\advance\tocsectotal by\tocsecnum
+\tocsubsectotal=\tocsectotal
+\advance\tocsubsectotal by\tocsubsecnum
+\tocsubsubsectotal=\tocsubsectotal
+\advance\tocsubsubsectotal by\tocsubsubsecnum
+\tocparatotal=\tocsubsubsectotal
+\advance\tocparatotal by\tocparanum}
+\calctocindent
+
+\def\l@section{\@dottedtocline{1}{\tocchpnum}{\tocsecnum}}
+\def\l@subsection{\@dottedtocline{2}{\tocsectotal}{\tocsubsecnum}}
+\def\l@subsubsection{\@dottedtocline{3}{\tocsubsectotal}{\tocsubsubsecnum}}
+\def\l@paragraph{\@dottedtocline{4}{\tocsubsubsectotal}{\tocparanum}}
+\def\l@subparagraph{\@dottedtocline{5}{\tocparatotal}{\tocsubparanum}}
+
+\def\listoffigures{\@restonecolfalse\if@twocolumn\@restonecoltrue\onecolumn
+ \fi\section*{\listfigurename\@mkboth{{\listfigurename}}{{\listfigurename}}}
+ \@starttoc{lof}\if@restonecol\twocolumn\fi}
+\def\l@figure{\@dottedtocline{1}{0em}{1.5em}}
+
+\def\listoftables{\@restonecolfalse\if@twocolumn\@restonecoltrue\onecolumn
+ \fi\section*{\listtablename\@mkboth{{\listtablename}}{{\listtablename}}}
+ \@starttoc{lot}\if@restonecol\twocolumn\fi}
+\let\l@table\l@figure
+
+\renewcommand\listoffigures{%
+ \section*{\listfigurename
+ \@mkboth{\listfigurename}{\listfigurename}}%
+ \@starttoc{lof}%
+ }
+
+\renewcommand\listoftables{%
+ \section*{\listtablename
+ \@mkboth{\listtablename}{\listtablename}}%
+ \@starttoc{lot}%
+ }
+
+\ifx\oribibl\undefined
+\ifx\citeauthoryear\undefined
+\renewenvironment{thebibliography}[1]
+ {\section*{\refname}
+ \def\@biblabel##1{##1.}
+ \small
+ \list{\@biblabel{\@arabic\c@enumiv}}%
+ {\settowidth\labelwidth{\@biblabel{#1}}%
+ \leftmargin\labelwidth
+ \advance\leftmargin\labelsep
+ \if@openbib
+ \advance\leftmargin\bibindent
+ \itemindent -\bibindent
+ \listparindent \itemindent
+ \parsep \z@
+ \fi
+ \usecounter{enumiv}%
+ \let\p@enumiv\@empty
+ \renewcommand\theenumiv{\@arabic\c@enumiv}}%
+ \if@openbib
+ \renewcommand\newblock{\par}%
+ \else
+ \renewcommand\newblock{\hskip .11em \@plus.33em \@minus.07em}%
+ \fi
+ \sloppy\clubpenalty4000\widowpenalty4000%
+ \sfcode`\.=\@m}
+ {\def\@noitemerr
+ {\@latex@warning{Empty `thebibliography' environment}}%
+ \endlist}
+\def\@lbibitem[#1]#2{\item[{[#1]}\hfill]\if@filesw
+ {\let\protect\noexpand\immediate
+ \write\@auxout{\string\bibcite{#2}{#1}}}\fi\ignorespaces}
+\newcount\@tempcntc
+\def\@citex[#1]#2{\if@filesw\immediate\write\@auxout{\string\citation{#2}}\fi
+ \@tempcnta\z@\@tempcntb\m@ne\def\@citea{}\@cite{\@for\@citeb:=#2\do
+ {\@ifundefined
+ {b@\@citeb}{\@citeo\@tempcntb\m@ne\@citea\def\@citea{,}{\bfseries
+ ?}\@warning
+ {Citation `\@citeb' on page \thepage \space undefined}}%
+ {\setbox\z@\hbox{\global\@tempcntc0\csname b@\@citeb\endcsname\relax}%
+ \ifnum\@tempcntc=\z@ \@citeo\@tempcntb\m@ne
+ \@citea\def\@citea{,}\hbox{\csname b@\@citeb\endcsname}%
+ \else
+ \advance\@tempcntb\@ne
+ \ifnum\@tempcntb=\@tempcntc
+ \else\advance\@tempcntb\m@ne\@citeo
+ \@tempcnta\@tempcntc\@tempcntb\@tempcntc\fi\fi}}\@citeo}{#1}}
+\def\@citeo{\ifnum\@tempcnta>\@tempcntb\else
+ \@citea\def\@citea{,\,\hskip\z@skip}%
+ \ifnum\@tempcnta=\@tempcntb\the\@tempcnta\else
+ {\advance\@tempcnta\@ne\ifnum\@tempcnta=\@tempcntb \else
+ \def\@citea{--}\fi
+ \advance\@tempcnta\m@ne\the\@tempcnta\@citea\the\@tempcntb}\fi\fi}
+\else
+\renewenvironment{thebibliography}[1]
+ {\section*{\refname}
+ \small
+ \list{}%
+ {\settowidth\labelwidth{}%
+ \leftmargin\parindent
+ \itemindent=-\parindent
+ \labelsep=\z@
+ \if@openbib
+ \advance\leftmargin\bibindent
+ \itemindent -\bibindent
+ \listparindent \itemindent
+ \parsep \z@
+ \fi
+ \usecounter{enumiv}%
+ \let\p@enumiv\@empty
+ \renewcommand\theenumiv{}}%
+ \if@openbib
+ \renewcommand\newblock{\par}%
+ \else
+ \renewcommand\newblock{\hskip .11em \@plus.33em \@minus.07em}%
+ \fi
+ \sloppy\clubpenalty4000\widowpenalty4000%
+ \sfcode`\.=\@m}
+ {\def\@noitemerr
+ {\@latex@warning{Empty `thebibliography' environment}}%
+ \endlist}
+ \def\@cite#1{#1}%
+ \def\@lbibitem[#1]#2{\item[]\if@filesw
+ {\def\protect##1{\string ##1\space}\immediate
+ \write\@auxout{\string\bibcite{#2}{#1}}}\fi\ignorespaces}
+ \fi
+\else
+\@cons\@openbib@code{\noexpand\small}
+\fi
+
+\def\idxquad{\hskip 10\p@}% space that divides entry from number
+
+\def\@idxitem{\par\hangindent 10\p@}
+
+\def\subitem{\par\setbox0=\hbox{--\enspace}% second order
+ \noindent\hangindent\wd0\box0}% index entry
+
+\def\subsubitem{\par\setbox0=\hbox{--\,--\enspace}% third
+ \noindent\hangindent\wd0\box0}% order index entry
+
+\def\indexspace{\par \vskip 10\p@ plus5\p@ minus3\p@\relax}
+
+\renewenvironment{theindex}
+ {\@mkboth{\indexname}{\indexname}%
+ \thispagestyle{empty}\parindent\z@
+ \parskip\z@ \@plus .3\p@\relax
+ \let\item\par
+ \def\,{\relax\ifmmode\mskip\thinmuskip
+ \else\hskip0.2em\ignorespaces\fi}%
+ \normalfont\small
+ \begin{multicols}{2}[\@makeschapterhead{\indexname}]%
+ }
+ {\end{multicols}}
+
+\renewcommand\footnoterule{%
+ \kern-3\p@
+ \hrule\@width 2truecm
+ \kern2.6\p@}
+ \newdimen\fnindent
+ \fnindent1em
+\long\def\@makefntext#1{%
+ \parindent \fnindent%
+ \leftskip \fnindent%
+ \noindent
+ \llap{\hb@xt@1em{\hss\@makefnmark\ }}\ignorespaces#1}
+
+\long\def\@makecaption#1#2{%
+ \vskip\abovecaptionskip
+ \sbox\@tempboxa{{\bfseries #1.} #2}%
+ \ifdim \wd\@tempboxa >\hsize
+ {\bfseries #1.} #2\par
+ \else
+ \global \@minipagefalse
+ \hb@xt@\hsize{\hfil\box\@tempboxa\hfil}%
+ \fi
+ \vskip\belowcaptionskip}
+
+\def\fps@figure{htbp}
+\def\fnum@figure{\figurename\thinspace\thefigure}
+\def \@floatboxreset {%
+ \reset@font
+ \small
+ \@setnobreak
+ \@setminipage
+}
+\def\fps@table{htbp}
+\def\fnum@table{\tablename~\thetable}
+\renewenvironment{table}
+ {\setlength\abovecaptionskip{0\p@}%
+ \setlength\belowcaptionskip{10\p@}%
+ \@float{table}}
+ {\end@float}
+\renewenvironment{table*}
+ {\setlength\abovecaptionskip{0\p@}%
+ \setlength\belowcaptionskip{10\p@}%
+ \@dblfloat{table}}
+ {\end@dblfloat}
+
+\long\def\@caption#1[#2]#3{\par\addcontentsline{\csname
+ ext@#1\endcsname}{#1}{\protect\numberline{\csname
+ the#1\endcsname}{\ignorespaces #2}}\begingroup
+ \@parboxrestore
+ \@makecaption{\csname fnum@#1\endcsname}{\ignorespaces #3}\par
+ \endgroup}
+
+% LaTeX does not provide a command to enter the authors institute
+% addresses. The \institute command is defined here.
+
+\newcounter{@inst}
+\newcounter{@auth}
+\newcounter{auco}
+\def\andname{and}
+\def\lastandname{\unskip, and}
+\newdimen\instindent
+\newbox\authrun
+\newtoks\authorrunning
+\newtoks\tocauthor
+\newbox\titrun
+\newtoks\titlerunning
+\newtoks\toctitle
+
+\def\clearheadinfo{\gdef\@author{No Author Given}%
+ \gdef\@title{No Title Given}%
+ \gdef\@subtitle{}%
+ \gdef\@institute{No Institute Given}%
+ \gdef\@thanks{}%
+ \global\titlerunning={}\global\authorrunning={}%
+ \global\toctitle={}\global\tocauthor={}}
+
+\def\institute#1{\gdef\@institute{#1}}
+
+\def\institutename{\par
+ \begingroup
+ \parskip=\z@
+ \parindent=\z@
+ \setcounter{@inst}{1}%
+ \def\and{\par\stepcounter{@inst}%
+ \noindent$^{\the@inst}$\enspace\ignorespaces}%
+ \setbox0=\vbox{\def\thanks##1{}\@institute}%
+ \ifnum\c@@inst=1\relax
+ \else
+ \setcounter{footnote}{\c@@inst}%
+ \setcounter{@inst}{1}%
+ \noindent$^{\the@inst}$\enspace
+ \fi
+ \ignorespaces
+ \@institute\par
+ \endgroup}
+
+\def\@fnsymbol#1{\ensuremath{\ifcase#1\or\star\or{\star\star}\or
+ {\star\star\star}\or \dagger\or \ddagger\or
+ \mathchar "278\or \mathchar "27B\or \|\or **\or \dagger\dagger
+ \or \ddagger\ddagger \else\@ctrerr\fi}}
+
+\def\inst#1{\unskip$^{#1}$}
+\def\fnmsep{\unskip$^,$}
+\def\email#1{{\tt#1}}
+\AtBeginDocument{\@ifundefined{url}{\def\url#1{#1}}{}}
+\def\homedir{\~{ }}
+
+\def\subtitle#1{\gdef\@subtitle{#1}}
+\clearheadinfo
+
+\renewcommand\maketitle{\newpage
+ \refstepcounter{chapter}%
+ \stepcounter{section}%
+ \setcounter{section}{0}%
+ \setcounter{subsection}{0}%
+ \setcounter{figure}{0}
+ \setcounter{table}{0}
+ \setcounter{equation}{0}
+ \setcounter{footnote}{0}%
+ \begingroup
+ \parindent=\z@
+ \renewcommand\thefootnote{\@fnsymbol\c@footnote}%
+ \if@twocolumn
+ \ifnum \col@number=\@ne
+ \@maketitle
+ \else
+ \twocolumn[\@maketitle]%
+ \fi
+ \else
+ \newpage
+ \global\@topnum\z@ % Prevents figures from going at top of page.
+ \@maketitle
+ \fi
+ \thispagestyle{empty}\@thanks
+%
+ \def\\{\unskip\ \ignorespaces}\def\inst##1{\unskip{}}%
+ \def\thanks##1{\unskip{}}\def\fnmsep{\unskip}%
+ \instindent=\hsize
+ \advance\instindent by-\headlineindent
+ \if!\the\toctitle!\addcontentsline{toc}{title}{\@title}\else
+ \addcontentsline{toc}{title}{\the\toctitle}\fi
+ \if@runhead
+ \if!\the\titlerunning!\else
+ \edef\@title{\the\titlerunning}%
+ \fi
+ \global\setbox\titrun=\hbox{\small\rm\unboldmath\ignorespaces\@title}%
+ \ifdim\wd\titrun>\instindent
+ \typeout{Title too long for running head. Please supply}%
+ \typeout{a shorter form with \string\titlerunning\space prior to
+ \string\maketitle}%
+ \global\setbox\titrun=\hbox{\small\rm
+ Title Suppressed Due to Excessive Length}%
+ \fi
+ \xdef\@title{\copy\titrun}%
+ \fi
+%
+ \if!\the\tocauthor!\relax
+ {\def\and{\noexpand\protect\noexpand\and}%
+ \protected@xdef\toc@uthor{\@author}}%
+ \else
+ \def\\{\noexpand\protect\noexpand\newline}%
+ \protected@xdef\scratch{\the\tocauthor}%
+ \protected@xdef\toc@uthor{\scratch}%
+ \fi
+ \addtocontents{toc}{{\protect\raggedright\protect\leftskip15\p@
+ \protect\rightskip\@tocrmarg
+ \protect\itshape\toc@uthor\protect\endgraf}}%
+ \if@runhead
+ \if!\the\authorrunning!
+ \value{@inst}=\value{@auth}%
+ \setcounter{@auth}{1}%
+ \else
+ \edef\@author{\the\authorrunning}%
+ \fi
+ \global\setbox\authrun=\hbox{\small\unboldmath\@author\unskip}%
+ \ifdim\wd\authrun>\instindent
+ \typeout{Names of authors too long for running head. Please supply}%
+ \typeout{a shorter form with \string\authorrunning\space prior to
+ \string\maketitle}%
+ \global\setbox\authrun=\hbox{\small\rm
+ Authors Suppressed Due to Excessive Length}%
+ \fi
+ \xdef\@author{\copy\authrun}%
+ \markboth{\@author}{\@title}%
+ \fi
+ \endgroup
+ \setcounter{footnote}{0}%
+ \clearheadinfo}
+%
+\def\@maketitle{\newpage
+ \markboth{}{}%
+ \def\lastand{\ifnum\value{@inst}=2\relax
+ \unskip{} \andname\
+ \else
+ \unskip \lastandname\
+ \fi}%
+ \def\and{\stepcounter{@auth}\relax
+ \ifnum\value{@auth}=\value{@inst}%
+ \lastand
+ \else
+ \unskip,
+ \fi}%
+ \begin{center}%
+ {\Large \bfseries\boldmath
+ \pretolerance=10000
+ \@title \par}\vskip .8cm
+\if!\@subtitle!\else {\large \bfseries\boldmath
+ \vskip -.65cm
+ \pretolerance=10000
+ \@subtitle \par}\vskip .8cm\fi
+ \setbox0=\vbox{\setcounter{@auth}{1}\def\and{\stepcounter{@auth}}%
+ \def\thanks##1{}\@author}%
+ \global\value{@inst}=\value{@auth}%
+ \global\value{auco}=\value{@auth}%
+ \setcounter{@auth}{1}%
+{\lineskip .5em
+\noindent\ignorespaces
+\@author\vskip.35cm}
+ {\small\institutename}
+ \end{center}%
+ }
+
+% definition of the "\spnewtheorem" command.
+%
+% Usage:
+%
+% \spnewtheorem{env_nam}{caption}[within]{cap_font}{body_font}
+% or \spnewtheorem{env_nam}[numbered_like]{caption}{cap_font}{body_font}
+% or \spnewtheorem*{env_nam}{caption}{cap_font}{body_font}
+%
+% New is "cap_font" and "body_font". It stands for
+% fontdefinition of the caption and the text itself.
+%
+% "\spnewtheorem*" gives a theorem without number.
+%
+% A defined spnewthoerem environment is used as described
+% by Lamport.
+%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+\def\@thmcountersep{}
+\def\@thmcounterend{.}
+
+\def\spnewtheorem{\@ifstar{\@sthm}{\@Sthm}}
+
+% definition of \spnewtheorem with number
+
+\def\@spnthm#1#2{%
+ \@ifnextchar[{\@spxnthm{#1}{#2}}{\@spynthm{#1}{#2}}}
+\def\@Sthm#1{\@ifnextchar[{\@spothm{#1}}{\@spnthm{#1}}}
+
+\def\@spxnthm#1#2[#3]#4#5{\expandafter\@ifdefinable\csname #1\endcsname
+ {\@definecounter{#1}\@addtoreset{#1}{#3}%
+ \expandafter\xdef\csname the#1\endcsname{\expandafter\noexpand
+ \csname the#3\endcsname \noexpand\@thmcountersep \@thmcounter{#1}}%
+ \expandafter\xdef\csname #1name\endcsname{#2}%
+ \global\@namedef{#1}{\@spthm{#1}{\csname #1name\endcsname}{#4}{#5}}%
+ \global\@namedef{end#1}{\@endtheorem}}}
+
+\def\@spynthm#1#2#3#4{\expandafter\@ifdefinable\csname #1\endcsname
+ {\@definecounter{#1}%
+ \expandafter\xdef\csname the#1\endcsname{\@thmcounter{#1}}%
+ \expandafter\xdef\csname #1name\endcsname{#2}%
+ \global\@namedef{#1}{\@spthm{#1}{\csname #1name\endcsname}{#3}{#4}}%
+ \global\@namedef{end#1}{\@endtheorem}}}
+
+\def\@spothm#1[#2]#3#4#5{%
+ \@ifundefined{c@#2}{\@latexerr{No theorem environment `#2' defined}\@eha}%
+ {\expandafter\@ifdefinable\csname #1\endcsname
+ {\global\@namedef{the#1}{\@nameuse{the#2}}%
+ \expandafter\xdef\csname #1name\endcsname{#3}%
+ \global\@namedef{#1}{\@spthm{#2}{\csname #1name\endcsname}{#4}{#5}}%
+ \global\@namedef{end#1}{\@endtheorem}}}}
+
+\def\@spthm#1#2#3#4{\topsep 7\p@ \@plus2\p@ \@minus4\p@
+\refstepcounter{#1}%
+\@ifnextchar[{\@spythm{#1}{#2}{#3}{#4}}{\@spxthm{#1}{#2}{#3}{#4}}}
+
+\def\@spxthm#1#2#3#4{\@spbegintheorem{#2}{\csname the#1\endcsname}{#3}{#4}%
+ \ignorespaces}
+
+\def\@spythm#1#2#3#4[#5]{\@spopargbegintheorem{#2}{\csname
+ the#1\endcsname}{#5}{#3}{#4}\ignorespaces}
+
+\def\@spbegintheorem#1#2#3#4{\trivlist
+ \item[\hskip\labelsep{#3#1\ #2\@thmcounterend}]#4}
+
+\def\@spopargbegintheorem#1#2#3#4#5{\trivlist
+ \item[\hskip\labelsep{#4#1\ #2}]{#4(#3)\@thmcounterend\ }#5}
+
+% definition of \spnewtheorem* without number
+
+\def\@sthm#1#2{\@Ynthm{#1}{#2}}
+
+\def\@Ynthm#1#2#3#4{\expandafter\@ifdefinable\csname #1\endcsname
+ {\global\@namedef{#1}{\@Thm{\csname #1name\endcsname}{#3}{#4}}%
+ \expandafter\xdef\csname #1name\endcsname{#2}%
+ \global\@namedef{end#1}{\@endtheorem}}}
+
+\def\@Thm#1#2#3{\topsep 7\p@ \@plus2\p@ \@minus4\p@
+\@ifnextchar[{\@Ythm{#1}{#2}{#3}}{\@Xthm{#1}{#2}{#3}}}
+
+\def\@Xthm#1#2#3{\@Begintheorem{#1}{#2}{#3}\ignorespaces}
+
+\def\@Ythm#1#2#3[#4]{\@Opargbegintheorem{#1}
+ {#4}{#2}{#3}\ignorespaces}
+
+\def\@Begintheorem#1#2#3{#3\trivlist
+ \item[\hskip\labelsep{#2#1\@thmcounterend}]}
+
+\def\@Opargbegintheorem#1#2#3#4{#4\trivlist
+ \item[\hskip\labelsep{#3#1}]{#3(#2)\@thmcounterend\ }}
+
+\if@envcntsect
+ \def\@thmcountersep{.}
+ \spnewtheorem{theorem}{Theorem}[section]{\bfseries}{\itshape}
+\else
+ \spnewtheorem{theorem}{Theorem}{\bfseries}{\itshape}
+ \if@envcntreset
+ \@addtoreset{theorem}{section}
+ \else
+ \@addtoreset{theorem}{chapter}
+ \fi
+\fi
+
+%definition of divers theorem environments
+\spnewtheorem*{claim}{Claim}{\itshape}{\rmfamily}
+\spnewtheorem*{proof}{Proof}{\itshape}{\rmfamily}
+\if@envcntsame % alle Umgebungen wie Theorem.
+ \def\spn@wtheorem#1#2#3#4{\@spothm{#1}[theorem]{#2}{#3}{#4}}
+\else % alle Umgebungen mit eigenem Zaehler
+ \if@envcntsect % mit section numeriert
+ \def\spn@wtheorem#1#2#3#4{\@spxnthm{#1}{#2}[section]{#3}{#4}}
+ \else % nicht mit section numeriert
+ \if@envcntreset
+ \def\spn@wtheorem#1#2#3#4{\@spynthm{#1}{#2}{#3}{#4}
+ \@addtoreset{#1}{section}}
+ \else
+ \def\spn@wtheorem#1#2#3#4{\@spynthm{#1}{#2}{#3}{#4}
+ \@addtoreset{#1}{chapter}}%
+ \fi
+ \fi
+\fi
+\spn@wtheorem{case}{Case}{\itshape}{\rmfamily}
+\spn@wtheorem{conjecture}{Conjecture}{\itshape}{\rmfamily}
+\spn@wtheorem{corollary}{Corollary}{\bfseries}{\itshape}
+\spn@wtheorem{definition}{Definition}{\bfseries}{\itshape}
+\spn@wtheorem{example}{Example}{\itshape}{\rmfamily}
+\spn@wtheorem{exercise}{Exercise}{\itshape}{\rmfamily}
+\spn@wtheorem{lemma}{Lemma}{\bfseries}{\itshape}
+\spn@wtheorem{note}{Note}{\itshape}{\rmfamily}
+\spn@wtheorem{problem}{Problem}{\itshape}{\rmfamily}
+\spn@wtheorem{property}{Property}{\itshape}{\rmfamily}
+\spn@wtheorem{proposition}{Proposition}{\bfseries}{\itshape}
+\spn@wtheorem{question}{Question}{\itshape}{\rmfamily}
+\spn@wtheorem{solution}{Solution}{\itshape}{\rmfamily}
+\spn@wtheorem{remark}{Remark}{\itshape}{\rmfamily}
+
+\def\@takefromreset#1#2{%
+ \def\@tempa{#1}%
+ \let\@tempd\@elt
+ \def\@elt##1{%
+ \def\@tempb{##1}%
+ \ifx\@tempa\@tempb\else
+ \@addtoreset{##1}{#2}%
+ \fi}%
+ \expandafter\expandafter\let\expandafter\@tempc\csname cl@#2\endcsname
+ \expandafter\def\csname cl@#2\endcsname{}%
+ \@tempc
+ \let\@elt\@tempd}
+
+\def\theopargself{\def\@spopargbegintheorem##1##2##3##4##5{\trivlist
+ \item[\hskip\labelsep{##4##1\ ##2}]{##4##3\@thmcounterend\ }##5}
+ \def\@Opargbegintheorem##1##2##3##4{##4\trivlist
+ \item[\hskip\labelsep{##3##1}]{##3##2\@thmcounterend\ }}
+ }
+
+\renewenvironment{abstract}{%
+ \list{}{\advance\topsep by0.35cm\relax\small
+ \leftmargin=1cm
+ \labelwidth=\z@
+ \listparindent=\z@
+ \itemindent\listparindent
+ \rightmargin\leftmargin}\item[\hskip\labelsep
+ \bfseries\abstractname]}
+ {\endlist}
+\renewcommand{\abstractname}{Abstract}
+\renewcommand{\contentsname}{Table of Contents}
+\renewcommand{\figurename}{Fig.}
+\renewcommand{\tablename}{Table}
+
+\newdimen\headlineindent % dimension for space between
+\headlineindent=1.166cm % number and text of headings.
+
+\def\ps@headings{\let\@mkboth\@gobbletwo
+ \let\@oddfoot\@empty\let\@evenfoot\@empty
+ \def\@evenhead{\normalfont\small\rlap{\thepage}\hspace{\headlineindent}%
+ \leftmark\hfil}
+ \def\@oddhead{\normalfont\small\hfil\rightmark\hspace{\headlineindent}%
+ \llap{\thepage}}
+ \def\chaptermark##1{}%
+ \def\sectionmark##1{}%
+ \def\subsectionmark##1{}}
+
+\def\ps@titlepage{\let\@mkboth\@gobbletwo
+ \let\@oddfoot\@empty\let\@evenfoot\@empty
+ \def\@evenhead{\normalfont\small\rlap{\thepage}\hspace{\headlineindent}%
+ \hfil}
+ \def\@oddhead{\normalfont\small\hfil\hspace{\headlineindent}%
+ \llap{\thepage}}
+ \def\chaptermark##1{}%
+ \def\sectionmark##1{}%
+ \def\subsectionmark##1{}}
+
+\if@runhead\ps@headings\else
+\ps@empty\fi
+
+\setlength\arraycolsep{1.4\p@}
+\setlength\tabcolsep{1.4\p@}
+
+\endinput
+
diff --git a/position-papers/W3C-Identity/usenix.sty b/position-papers/W3C-Identity/usenix.sty
new file mode 100644
index 0000000..22935a7
--- /dev/null
+++ b/position-papers/W3C-Identity/usenix.sty
@@ -0,0 +1,97 @@
+% usenix-2e.sty - to be used with latex2e (the new one) for USENIX.
+% To use this style file, do this:
+%
+% \documentclass[twocolumn]{article}
+% \usepackage{usenix-2e}
+% and put {\rm ....} around the author names.
+%
+% The following definitions are modifications of standard article.sty
+% definitions, arranged to do a better job of matching the USENIX
+% guidelines.
+% It will automatically select two-column mode and the Times-Roman
+% font.
+
+%
+% USENIX papers are two-column.
+% Times-Roman font is nice if you can get it (requires NFSS,
+% which is in latex2e.
+
+%\if@twocolumn\else\input twocolumn.sty\fi
+\usepackage{times}
+
+%
+% USENIX wants margins of: 7/8" side, 1" bottom, and 3/4" top.
+% 0.25" gutter between columns.
+% Gives active areas of 6.75" x 9.25"
+%
+\setlength{\textheight}{9.0in}
+\setlength{\columnsep}{0.25in}
+\setlength{\textwidth}{6.75in}
+%\setlength{\textwidth}{7.00in}
+%\setlength{\footheight}{0.0in}
+\setlength{\topmargin}{-0.25in}
+\setlength{\headheight}{0.0in}
+\setlength{\headsep}{0.0in}
+\setlength{\evensidemargin}{-0.125in}
+\setlength{\oddsidemargin}{-0.125in}
+
+%
+% Usenix wants no page numbers for submitted papers, so that they can
+% number them themselves.
+%
+\pagestyle{empty}
+
+%
+% Usenix titles are in 14-point bold type, with no date, and with no
+% change in the empty page headers. The whol author section is 12 point
+% italic--- you must use {\rm } around the actual author names to get
+% them in roman.
+%
+\def\maketitle{\par
+ \begingroup
+ \renewcommand\thefootnote{\fnsymbol{footnote}}%
+ \def\@makefnmark{\hbox to\z@{$\m@th^{\@thefnmark}$\hss}}%
+ \long\def\@makefntext##1{\parindent 1em\noindent
+ \hbox to1.8em{\hss$\m@th^{\@thefnmark}$}##1}%
+ \if@twocolumn
+ \twocolumn[\@maketitle]%
+ \else \newpage
+ \global\@topnum\z@
+ \@maketitle \fi\@thanks
+ \endgroup
+ \setcounter{footnote}{0}%
+ \let\maketitle\relax
+ \let\@maketitle\relax
+ \gdef\@thanks{}\gdef\@author{}\gdef\@title{}\let\thanks\relax}
+
+\def\@maketitle{\newpage
+ %\vbox to 0.5in{
+ \vbox to 1.5in{
+ %\vspace*{\fill}
+ %\vskip 2em
+ \begin{center}%
+ {\Large\bf \@title \par}%
+ \vskip 0.250in minus 0.250in
+ {\large\it
+ \lineskip .5em
+ \begin{tabular}[t]{c}\@author
+ \end{tabular}\par}%
+ \end{center}%
+ \par
+ \vspace*{\fill}
+% \vskip 1.5em
+ }
+}
+
+%
+% The abstract is preceded by a 12-pt bold centered heading
+\def\abstract{\begin{center}%
+{\large\bf \abstractname\vspace{-.5em}\vspace{\z@}}%
+\end{center}}
+\def\endabstract{}
+
+%
+% Main section titles are 12-pt bold. Others can be same or smaller.
+%
+\def\section{\@startsection {section}{1}{\z@}{-3.5ex plus-1ex minus
+ -.2ex}{2.3ex plus.2ex}{\reset@font\large\bf}}
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