% ============================================================================
% philphys.bst -- Philosophy of Physics BibTeX style, v1.0.1 (2026-10-14)
% ============================================================================
%
% A modification of Chicago style for the journal Philosophy of Physics.
%
% Modifications copyright 2026 Bryan W Roberts.
% Distributed and/or modified under LPPL 1.3c or any later version.
% This file is part of the maintained philphys work listed in LICENSE.txt.
% Current maintainer: Bryan W Roberts; philphyssociety@gmail.com.
% The original attribution and copying notice remain below.
% Journal adaptation of Glenn Paulley's chicago.bst version 4 (1992-08-28).
% Upstream downloaded from CTAN on 2026-10-07:
% https://mirrors.ctan.org/biblio/bibtex/contrib/chicago/chicago.bst
% The upstream attribution and copying notice are retained verbatim below.
% This derivative has a distinct filename; upstream metadata below describes
% chicago.bst, not this modified file. The journal changes are marked POP.
%
% USAGE (with philphys.cls, which already loads natbib and url):
%   \bibliographystyle{philphys}
%   \bibliography{philphys-sample-bibliography}
% Compile LaTeX, BibTeX, LaTeX, LaTeX, or use latexmk -pdf.
% Do not load the obsolete chicago.sty mentioned in the upstream comments.
%
%
% DATA CONVENTIONS / SUPPORTED EXTENSIONS:
%   Use ordinary BibTeX fields, not biblatex date/journaltitle/location fields.
%   Titles retain exactly the supplied case; enter the desired title case yourself.
%   Protect TeX accents and special names, e.g. D{\"u}rr and {{Planck Collaboration}}.
%   DOI accepts a bare identifier, doi:identifier, or http(s)://(dx.)doi.org/...
%   eid (or articleno) can supply an article identifier when pages is absent.
%   eprint plus archiveprefix=arXiv supplies a link when url is absent.
%   urldate is optional free-form text, e.g. {7 October 2026}.
%   edition is an ordinal without "ed.", e.g. {2nd}; year may be {forthcoming}.
%   Missing year becomes n.d.; initials, particles, suffixes and corporate names
%   follow standard BibTeX name parsing. There is no automatic title-case conversion.
%   Crossref inheritance works; put booktitle on the parent/child for chapters.
%
% MAINTENANCE MAP:
%   format.names / format.authors / format.editors: printed names and boldface.
%   format.title / format.btitle: quotation, punctuation and title capitalization.
%   format.jour.vol / format.pages: issue, pages and article-ID punctuation.
%   format.in.ed.booktitle: chapter container and editor order.
%   normalize.doi / format.url / format.doi / fin.entry: electronic references.
%   calc.label / presort / forward.pass / pop.alpha.suffix: plain labels and suffixes.
%   Entry-type functions: ordering of fields. TeX layout stays in philphys.cls.
%
% ============================================================================
% ORIGINAL chicago.bst HEADER / ATTRIBUTION / COPYING NOTICE (unchanged):
% ============================================================================
%%% ====================================================================
%%%  @BibTeX-style-file{
%%%     author          = "Glenn Paulley",
%%%     version         = "4",
%%%     date            = "28 August 1992",
%%%     time            = "10:23:39 199",
%%%     filename        = "chicago.bst",
%%%     address         = "Data Structuring Group
%%%                        Department of Computer Science
%%%                        University of Waterloo
%%%                        Waterloo, Ontario, Canada
%%%                        N2L 3G1",
%%%     telephone       = "(519) 885-1211",
%%%     FAX             = "(519) 885-1208",
%%%     checksum        = "26323 1654 5143 37417",
%%%     email           = "gnpaulle@bluebox.uwaterloo.ca",
%%%     codetable       = "ISO/ASCII",
%%%     keywords        = "",
%%%     supported       = "yes",
%%%     abstract        = "A BibTeX bibliography style that follows the
%%%                        `B' reference style of the 13th Edition of
%%%                        the Chicago Manual of Style. A detailed
%%%                        feature list is given below.",
%%%     docstring       = "The checksum field above contains a CRC-16
%%%                        checksum as the first value, followed by the
%%%                        equivalent of the standard UNIX wc (word
%%%                        count) utility output of lines, words, and
%%%                        characters.  This is produced by Robert
%%%                        Solovay's checksum utility.",
%%%  }
%%% ====================================================================
%
% "Chicago" BibTeX style, chicago.bst
% ===================================
%
% BibTeX `chicago' style file for BibTeX version 0.99c, LaTeX version 2.09
% Place it in a file called chicago.bst in the BibTeX search path.
% You need to include chicago.sty as a \documentstyle option.
% (Placing it in the same directory as the LaTeX document should also work.)
% This "chicago" style is based on newapa.bst (American Psych. Assoc.)
% found at ymir.claremont.edu.
%
%   Citation format: (author-last-name year)
%             (author-last-name and author-last-name year)
%             (author-last-name, author-last-name, and author-last-name year)
%             (author-last-name et al. year)
%             (author-last-name)
%             author-last-name (year)
%             (author-last-name and author-last-name)
%             (author-last-name et al.)
%             (year) or (year,year)
%             year or year,year
%
%   Reference list ordering: alphabetical by author or whatever passes
%    for author in the absence of one.
%
% This BibTeX style has support for abbreviated author lists and for
%    year-only citations.  This is done by having the citations
%    actually look like
%
%    \citeauthoryear{full-author-info}{abbrev-author-info}{year}
%
% The LaTeX style has to have the following (or similar)
%
%     \let\@internalcite\cite
%     \def\fullcite{\def\citeauthoryear##1##2##3{##1, ##3}\@internalcite}
%     \def\fullciteA{\def\citeauthoryear##1##2##3{##1}\@internalcite}
%     \def\shortcite{\def\citeauthoryear##1##2##3{##2, ##3}\@internalcite}
%     \def\shortciteA{\def\citeauthoryear##1##2##3{##2}\@internalcite}
%     \def\citeyear{\def\citeauthoryear##1##2##3{##3}\@internalcite}
%
% These TeX macro definitions are found in chicago.sty. Additional
% commands to manipulate different components of a citation can be defined
% so that, for example, you can list author's names without parentheses
% if using a citation as a noun or object in a sentence.
%
% This file was originally copied from newapa.bst at ymir.claremont.edu.
%
% Features of chicago.bst:
% =======================
%
% - full names used in citations, but abbreviated citations are available
%   (see above)
% - if an entry has a "month", then the month and year are also printed
%   as part of that bibitem.
% - all conjunctions use "and" instead of "\&"
% - major modification from Chicago Manual of Style (13th ed.) is that
%   only the first author in a reference appears last name first-
%   additional authors appear as J. Q. Public.
% - pages are listed as "pp. xx-xx" in all entry types except
%   article entries.
% - book, inbook, and manual use "location: publisher" (or organization)
%   for address and publisher. All other types list publishers separately.
% - "pp." are used to identify page numbers for all entry types except
%   articles.
% - organization is used as a citation label if neither author nor editor
%   is present (for manuals).
% - "et al." is used for long author and editor lists, or when "others"
%   is used.
%
% Modifications and bug fixes from newapa.bst:
% ===========================================
%
%   - added month, year to bib entries if month is present
%   - fixed bug with In proceedings, added necessary comma after title
%   - all conjunctions changed to "and" from "\&"
%   - fixed bug with author labels in my.full.label: "et al." now is
%        generated when "others" is an author name
%   - major modification from Chicago Manual of Style (13th ed.) is that
%     only the first author in a reference appears last name first-
%     additional authors appear as J. Q. Public.
%   - pages are listed as "pp. xx-xx" in all entry types except
%     article entries. Unnecessary (IMHO) "()" around page numbers
%     were removed, and page numbers now don't end with a period.
%   - created chicago.sty for use with this bibstyle (required).
%   - fixed bugs in FUNCTION {format.vol.num.pages} for missing volume,
%     number, and /or pages. Renamed to format.jour.vol.
%   - fixed bug in formatting booktitles: additional period an error if
%     book has a volume.
%   - fixed bug: editors usually given redundant period before next clause
%     (format.editors.dot) removed.
%   - added label support for organizations, if both author and editor
%     are missing (from alpha.bst). If organization is too long, then
%     the key field is used for abbreviated citations.
%   - In proceedings or books of several volumes, no comma was written
%     between the "Volume x" and the page numbers (this was intentional
%     in newapa.bst). Fixed.
%   - Some journals may not have volumes/numbers, only month/year (eg.
%     IEEE Computer). Fixed bug in article style that assumed volume/number
%     was always present.
%
% Original documentation for newapa.sty:
% =====================================
%
% This version was made by modifying the master file made by
% Oren Patashnik (PATASHNIK@SCORE.STANFORD.EDU), and the 'named' BibTeX
% style of Peter F. Patel-Schneider.
%
% Copyright (C) 1985, all rights reserved.
% Copying of this file is authorized only if either
% (1) you make absolutely no changes to your copy, including name, or
% (2) if you do make changes, you name it something other than 'newapa.bst'.
% There are undoubtably bugs in this style.  If you make bug fixes,
% improvements, etc.  please let me know.  My e-mail address is:
%    spencer@cgrg.ohio.state.edu or 71160.3141@compuserve.com
%
% This style was made from 'plain.bst', 'named.bst', and 'apalike.bst',
% with lots of tweaking to make it look like APA style, along with tips
% from Young Ryu and Brian Reiser's modifications of 'apalike.bst'.

ENTRY
  { address
    author
    booktitle
    chapter
    edition
    doi
    url
    urldate
    eid
    articleno
    eprint
    archiveprefix
    editor
    howpublished
    institution
    journal
    key
    month
    note
    number
    organization
    pages
    publisher
    school
    series
    title
    type
    volume
    year
  }
  {}
  { label.year label.short extra.label sort.year sort.label }

INTEGERS { output.state before.all mid.sentence after.sentence after.block }

FUNCTION {init.state.consts}
{ #0 'before.all :=
  #1 'mid.sentence :=
  #2 'after.sentence :=
  #3 'after.block :=
}

STRINGS { s t u }

% POP: The terminal mark is already INSIDE a quoted title. BibTeX's built-in
% add.period$ cannot recognize TeX closing quotes and would append a second dot.
FUNCTION {pop.add.period}
{ duplicate$ #-1 #2 substring$ "''" =
    'skip$
    'add.period$
  if$
}

FUNCTION {output.nonnull}
{ 's :=
  output.state mid.sentence =
    { ", " * write$ }
    { output.state after.block =
    { pop.add.period write$
      newline$
      "\newblock " write$
    }
    { output.state before.all =
        'write$
        { pop.add.period " " * write$ }
      if$
    }
      if$
      mid.sentence 'output.state :=
    }
  if$
  s
}

% Use a colon to separate output. Used only for address/publisher
% combination in book/inbook types, address/institution for manuals,
% and organization:publisher for proceedings (inproceedings).
%
FUNCTION {output.nonnull.colon}
{ 's :=
  output.state mid.sentence =
    { ": " * write$ }
    { output.state after.block =
    { pop.add.period write$
      newline$
      "\newblock " write$
    }
    { output.state before.all =
        'write$
        { pop.add.period " " * write$ }
      if$
    }
      if$
      mid.sentence 'output.state :=
    }
  if$
  s
}

FUNCTION {output}
{ duplicate$ empty$
    'pop$
    'output.nonnull
  if$
}

FUNCTION {output.colon}
{ duplicate$ empty$
    'pop$
    'output.nonnull.colon
  if$
}

FUNCTION {output.check}
{ 't :=
  duplicate$ empty$
    { pop$ "empty " t * " in " * cite$ * warning$ }
    'output.nonnull
  if$
}

FUNCTION {output.check.colon}
{ 't :=
  duplicate$ empty$
    { pop$ "empty " t * " in " * cite$ * warning$ }
    'output.nonnull.colon
  if$
}

% POP: Flush the leading name, then print the bare year. Month is not an author-year label.
FUNCTION {output.year.check}
{ pop.add.period write$
  " " write$
  year empty$ { "n.d." } { year } if$
  extra.label *
  mid.sentence 'output.state :=
}


FUNCTION {field.or.null}
{ duplicate$ empty$
    { pop$ "" }
    'skip$
  if$
}

FUNCTION {not}
{   { #0 }
    { #1 }
  if$
}

FUNCTION {and}
{   'skip$
    { pop$ #0 }
  if$
}

FUNCTION {or}
{   { pop$ #1 }
    'skip$
  if$
}

% POP: Normalize identifiers for linking and duplicate-URL comparison only.
% Never normalize titles or personal names. Leading/trailing spaces are trimmed.
FUNCTION {trim.spaces}
{ 'u :=
  { u empty$ not u #1 #1 substring$ " " = and }
  { u #2 global.max$ substring$ 'u := }
  while$
  { u empty$ not u #-1 #1 substring$ " " = and }
  { u #1 u text.length$ #1 - substring$ 'u := }
  while$
  u
}
FUNCTION {normalize.doi}
{ doi field.or.null trim.spaces 'u :=
  u #1 #19 substring$ "https://dx.doi.org/" =
    { u #20 global.max$ substring$ 'u := }
    'skip$
  if$
  u #1 #18 substring$ "http://dx.doi.org/" =
    { u #19 global.max$ substring$ 'u := }
    'skip$
  if$
  u #1 #16 substring$ "https://doi.org/" =
    { u #17 global.max$ substring$ 'u := }
    'skip$
  if$
  u #1 #15 substring$ "http://doi.org/" =
    { u #16 global.max$ substring$ 'u := }
    'skip$
  if$
  u #1 #4 substring$ "doi:" =
    { u #5 global.max$ substring$ trim.spaces 'u := }
    'skip$
  if$
  u
}
FUNCTION {format.doi}
{ doi empty$
    { "" }
    { "DOI: \url{https://doi.org/" normalize.doi * "}" * }
  if$
}
FUNCTION {format.url}
{ url empty$
    { eprint empty$
        { "" }
        { archiveprefix empty$ archiveprefix field.or.null "l" change.case$ "arxiv" = or
            { "\url{https://arxiv.org/abs/" eprint * "}" * }
            { archiveprefix ": " * eprint * }
          if$
        }
      if$
    }
    { url trim.spaces 't :=
      doi empty$
        { "\url{" t * "}" * }
        { normalize.doi 's :=
          t "https://doi.org/" s * =
          t "http://doi.org/" s * = or
          t "https://dx.doi.org/" s * = or
          t "http://dx.doi.org/" s * = or
            { "" }
            { "\url{" t * "}" * }
          if$
        }
      if$
    }
  if$
}

% POP: Append a distinct URL (or arXiv eprint link), access date, and DOI to every type.
FUNCTION {fin.entry}
{ output.state before.all = 'skip$ { after.block 'output.state := } if$
  format.url output
  urldate empty$ 'skip$ { "Accessed " urldate * output } if$
  output.state before.all = 'skip$ { after.block 'output.state := } if$
  format.doi output
  pop.add.period write$ newline$
}

FUNCTION {new.block}
{ output.state before.all =
    'skip$
    { after.block 'output.state := }
  if$
}

FUNCTION {new.sentence}
{ output.state after.block =
    'skip$
    { output.state before.all =
    'skip$
    { after.sentence 'output.state := }
      if$
    }
  if$
}

FUNCTION {new.block.checka}
{ empty$
    'skip$
    'new.block
  if$
}

FUNCTION {new.block.checkb}
{ empty$
  swap$ empty$
  and
    'skip$
    'new.block
  if$
}

FUNCTION {new.sentence.checka}
{ empty$
    'skip$
    'new.sentence
  if$
}

FUNCTION {new.sentence.checkb}
{ empty$
  swap$ empty$
  and
    'skip$
    'new.sentence
  if$
}



%
% Emphasize the top string on the stack.
%
FUNCTION {emphasize}
{ duplicate$ empty$
    { pop$ "" }
    { "{\em " swap$ * "}" * }
  if$
}

%
% Emphasize the top string on the stack, but add a trailing space.
%
FUNCTION {emphasize.space}
{ duplicate$ empty$
    { pop$ "" }
    { "{\em " swap$ * "\/}" * }
  if$
}

INTEGERS { nameptr namesleft numnames }
%
% Format bibliographical entries with the first author last name first,
% and subsequent authors with supplied given names followed by last name.
% All names are formatted in this routine.
%
% POP: Local bold group for one name (or an organization fallback), not a list.
% Never call this from sorting/citation-label functions.
FUNCTION {bold.names}
{ duplicate$ empty$ { pop$ "" } { "\textbf{" swap$ * "}" * } if$ }

% POP: Full given names; invert only the first name; Oxford comma even for two authors.
% Bold names individually so separators, "and", and "et al." remain unbolded.
FUNCTION {format.names}
{ 's :=
  #1 'nameptr :=
  s num.names$ 'numnames :=
  numnames 'namesleft :=
    { namesleft #0 > }
    { nameptr #1 =
        { s nameptr "{vv~}{ll}{, ff}{, jj}" format.name$ 't := }
        { s nameptr "{ff~}{vv~}{ll}{, jj}" format.name$ 't := }
      if$
      nameptr #1 >
        { t "others" =
            { ", et~al." * }
            { t bold.names 't :=
              namesleft #1 > { ", " * t * } { ", and " * t * } if$
            }
          if$
        }
        { t bold.names }
      if$
      nameptr #1 + 'nameptr :=
      namesleft #1 - 'namesleft :=
    }
  while$
}

FUNCTION {my.full.label}
{ 's :=
  #1 'nameptr :=               % nameptr = 1;
  s num.names$ 'numnames :=    % numnames = num.name$(s);
  numnames 'namesleft :=
    { namesleft #0 > }

    { s nameptr "{vv~}{ll}" format.name$ 't :=  % get the next name
      nameptr #1 >
        { namesleft #1 >
              { ", " * t * }
              { numnames #2 >
                  { "," * }
                  'skip$
                if$
                t "others" =
                    { " et~al." * }
                    { " and " * t * } % from Chicago Manual of Style
                  if$
               }
               if$
             }
            't
        if$
        nameptr #1 + 'nameptr :=          % nameptr += 1;
        namesleft #1 - 'namesleft :=      % namesleft =- 1;
    }
  while$

}

% POP: Embedded editor names, without inversion or boldface.
FUNCTION {format.names.fml}
%
% Format names in "familiar" format, with full given names followed by
% last name. Like format.names, ALL names are formatted.
%
{ 's :=
  #1 'nameptr :=               % nameptr = 1;
  s num.names$ 'numnames :=    % numnames = num.name$(s);
  numnames 'namesleft :=
    { namesleft #0 > }

    { s nameptr "{ff~}{vv~}{ll}{, jj}" format.name$ 't :=

      nameptr #1 >
        { namesleft #1 >
              { ", " * t * }
               { numnames #2 >
                    { "," * }
                    'skip$
                  if$
                  t "others" =
                        { " et~al." * }
                        { " and " * t * }
%                       { " \& " * t * }
                      if$
                }
               if$
             }
            't
        if$
        nameptr #1 + 'nameptr :=          % nameptr += 1;
        namesleft #1 - 'namesleft :=      % namesleft =- 1;
    }
  while$
}

FUNCTION {format.authors}
{ author empty$ { "" } { author format.names } if$ }

FUNCTION {format.key}
{ empty$
    { key field.or.null }
    { "" }
  if$
}

%
% Format embedded editor names for chapter/container text: supplied given
% names, then last names. Leading editor names use format.editors instead.
% Citation labels are built separately by calc.label. Embedded editors are
% neither abbreviated nor bold.
%
% POP: Embedded editors use full names in normal order, without bold or Ed./Eds. suffixes.
FUNCTION {format.editors.fml}
{ editor empty$ { "" } { editor format.names.fml } if$ }

%
% Format leading editor names in bibliography entries, inverting only the first.
%
% POP: Editor-led books/proceedings use bold leading names; the role remains outside bold.
FUNCTION {format.editors}
{ editor empty$
    { "" }
    { editor format.names
      editor num.names$ #1 > { ", eds." * } { ", ed." * } if$
    }
  if$
}

STRINGS { title.text title.quotes }

% POP: Punctuate the raw title before wrapping it in bibliography quotes.
% If the title itself ends in TeX double quotes, temporarily remove those
% closing pairs so punctuation is checked/added inside them. Negative-index
% substring$ preserves the raw TeX string, including braces and accent commands.
% pop.add.period is only for output strings whose outer quotes already exist.
FUNCTION {pop.title.period}
{ 'title.text :=
  "" 'title.quotes :=
  { title.text #-1 #2 substring$ "''" = }
  { title.text #-3 global.max$ substring$ 'title.text :=
    "''" title.quotes * 'title.quotes :=
  }
  while$
  title.text add.period$ title.quotes *
}

% POP: Preserve input capitalization and put terminal punctuation inside quotes.
FUNCTION {format.title}
{ title empty$ { "" } { "``" title pop.title.period * "''" * } if$ }

FUNCTION {n.dashify}
{ 't :=
  ""
    { t empty$ not }
    { t #1 #1 substring$ "-" =
    { t #1 #2 substring$ "--" = not
        { "--" *
          t #2 global.max$ substring$ 't :=
        }
        {   { t #1 #1 substring$ "-" = }
        { "-" *
          t #2 global.max$ substring$ 't :=
        }
          while$
        }
      if$
    }
    { t #1 #1 substring$ *
      t #2 global.max$ substring$ 't :=
    }
      if$
    }
  while$
}

% POP: Book titles italic; edition outside italics, e.g. 2nd ed. (enter edition={2nd}).
FUNCTION {format.btitle}
{ title empty$
    { "" }
    { title emphasize
      edition empty$ 'skip$ { ". " * edition * " ed." * } if$
    }
  if$
}

FUNCTION {format.emphasize.booktitle}
{ booktitle empty$
    { "" }
    { booktitle emphasize
      edition empty$ 'skip$ { ", " * edition * " ed." * } if$
    }
  if$
}


FUNCTION {tie.or.space.connect}
{ duplicate$ text.length$ #3 <
    { "~" }
    { " " }
  if$
  swap$ * *
}

FUNCTION {either.or.check}
{ empty$
    'pop$
    { "can't use both " swap$ * " fields in " * cite$ * warning$ }
  if$
}

FUNCTION {format.bvolume}
{ volume empty$
    { "" }
    { "Volume" volume tie.or.space.connect % gnp - changed to mixed case
      series empty$
        'skip$
        { " of " * series emphasize * }
      if$
      "volume and number" number either.or.check
    }
  if$
}

FUNCTION {format.number.series}
{ volume empty$
    { number empty$
    { series field.or.null }
    { output.state mid.sentence =
        { "Number" } % gnp - changed to mixed case always
        { "Number" }
      if$
      number tie.or.space.connect
      series empty$
        { "there's a number but no series in " cite$ * warning$ }
        { " in " * series * }
      if$
    }
      if$
    }
    { "" }
  if$
}

INTEGERS { multiresult }

FUNCTION {multi.page.check}
{ 't :=
  #0 'multiresult :=
    { multiresult not
      t empty$ not
      and
    }
    { t #1 #1 substring$
      duplicate$ "-" =
      swap$ duplicate$ "," =
      swap$ "+" =
      or or
    { #1 'multiresult := }
    { t #2 global.max$ substring$ 't := }
      if$
    }
  while$
  multiresult
}

% POP: Full page ranges; no pp. prefix. n.dashify turns single hyphens into TeX en dashes.
FUNCTION {format.pages}
{ pages empty$ { "" } { pages n.dashify } if$ }

% By Young (and Spencer)
% GNP - fixed bugs with missing volume, number, and/or pages
%
% Format journal, volume, number, pages for article types.
%
% POP: Italic journal, plain volume, spaced issue, colon before pages/eid/articleno; allow advance articles.
FUNCTION {format.jour.vol}
{ journal empty$
    { "no journal in " cite$ * warning$ "" }
    { journal emphasize }
  if$
  volume empty$ 'skip$ { " " * volume * } if$
  number empty$ 'skip$ { " (" * number * ")" * } if$
  pages empty$
    { eid empty$
        { articleno empty$ { "" } { articleno } if$ }
        { eid }
      if$
    }
    { pages n.dashify }
  if$
  duplicate$ empty$
    'pop$
    { swap$ duplicate$ empty$ { pop$ }
        { volume empty$ number empty$ and { ", " } { ": " } if$ * swap$ * }
      if$ }
  if$
}

FUNCTION {format.chapter.pages}
{ chapter empty$
    'format.pages
    { type empty$
        { "Chapter" } % gnp - changed to mixed case
        { type "t" change.case$ }
      if$
      chapter tie.or.space.connect
      pages empty$
        {"page numbers missing in " cite$ * warning$} % gnp - added check
        { ", " * format.pages * }
      if$
    }
  if$
}

% POP: Book title precedes embedded editor names, as in the published PoP chapters.
FUNCTION {format.in.ed.booktitle}
{ booktitle empty$
    { "" }
    { "In " format.emphasize.booktitle *
      editor empty$ 'skip$ { ", edited by " * format.editors.fml * } if$
    }
  if$
}

FUNCTION {format.thesis.type}
{ type empty$
    'skip$
    { pop$
      type "t" change.case$
    }
  if$
}

FUNCTION {format.tr.number}
{ type empty$
    { "Technical Report" }
    'type
  if$
  number empty$
    { "t" change.case$ }
    { number tie.or.space.connect }
  if$
}

FUNCTION {format.article.crossref}
{ "See"
  "\citet{" * crossref * "}" *
}

FUNCTION {format.crossref.editor}
{ editor #1 "{vv~}{ll}" format.name$
  editor num.names$ duplicate$
  #2 >
    { pop$ " et~al." * }
    { #2 <
    'skip$
    { editor #2 "{ff }{vv }{ll}{ jj}" format.name$ "others" =
        { " et~al." * }
        { " and " * editor #2 "{vv~}{ll}" format.name$ * }
      if$
    }
      if$
    }
  if$
}

FUNCTION {format.book.crossref}
{ volume empty$
    { "empty volume in " cite$ * "'s crossref of " * crossref * warning$
      "In "
    }
    { "Volume" volume tie.or.space.connect % gnp - changed to mixed case
      " of " *
    }
  if$
  editor empty$
  editor field.or.null author field.or.null =
  or
    { key empty$
    { series empty$
        { "need editor, key, or series for " cite$ * " to crossref " *
          crossref * warning$
          "" *
        }
        { "{\em " * series * "\/}" * }
      if$
    }
    { key * }
      if$
    }
    { format.crossref.editor * }
  if$
  " \citet{" * crossref * "}" *
}

FUNCTION {format.incoll.inproc.crossref}
{ "See"
  " \citet{" * crossref * "}" *
}

% format.lab.names:
%
% determines "short" names for the abbreviated author information.
% "Long" labels are created in calc.label, using the routine my.full.label
% to format author and editor fields. The abbreviated label uses et al.
% for three or more authors; starred natbib commands use the full label.
%
% Short labels: one author -> Foo; two authors -> Foo and Bar;
% three or more authors, or an explicit "and others" -> Foo et al.
% Full labels retain all supplied names for starred natbib commands.
%
FUNCTION {format.lab.names}
{ 's :=
  s num.names$ 'numnames :=
  numnames #2 >    % change number to number of others allowed before
		   % forcing "et al".
    { s #1 "{vv~}{ll}" format.name$ " et~al." * }
    {
      numnames #1 - 'namesleft :=
      #2 'nameptr :=
      s #1 "{vv~}{ll}" format.name$
	{ namesleft #0 > }
	{ nameptr numnames =
	    { s nameptr "{ff }{vv }{ll}{ jj}" format.name$ "others" =
		{ " et~al." * }
		{ " and " * s nameptr "{vv~}{ll}" format.name$ * }
	      if$
	    }
	    { ", " * s nameptr "{vv~}{ll}" format.name$ * }
	  if$
	  nameptr #1 + 'nameptr :=
	  namesleft #1 - 'namesleft :=
	}
      while$
    }
  if$
}

FUNCTION {author.key.label}
{ author empty$
    { key empty$
          { "no key, author in " cite$ * warning$
            cite$ #1 #3 substring$ }
         'key
      if$
    }
    { author format.lab.names }
  if$
}

FUNCTION {editor.key.label}
{ editor empty$
    { key empty$
          { "no key, editor in " cite$ * warning$
            cite$ #1 #3 substring$ }
          'key
        if$
     }
     { editor format.lab.names }
  if$
}

FUNCTION {author.key.organization.label}
%
% added - gnp. Provide label formatting by organization if author is null.
%
{ author empty$
    { organization empty$
	{ key empty$
	    { "no key, author or organization in " cite$ * warning$
              cite$ #1 #3 substring$ }
	    'key
	  if$
	}
        { organization }
      if$
    }
    { author format.lab.names }
  if$
}

FUNCTION {editor.key.organization.label}
%
% added - gnp. Provide label formatting by organization if editor is null.
%
{ editor empty$
    { organization empty$
	{ key empty$
	    { "no key, editor or organization in " cite$ * warning$
              cite$ #1 #3 substring$ }
	    'key
	  if$
	}
        { organization }
      if$
    }
    { editor format.lab.names }
  if$
}

FUNCTION {author.editor.key.label}
{ author empty$
    { editor empty$
          { key empty$
               { "no key, author, or editor in " cite$ * warning$
                 cite$ #1 #3 substring$ }
             'key
           if$
         }
          { editor format.lab.names }
      if$
    }
    { author format.lab.names }
  if$
}

% POP: Plain natbib short/full author labels; preserve forthcoming and n.d. instead of last four characters.
FUNCTION {calc.label}
{ author empty$
    { editor empty$
        { organization empty$
            { key empty$ { "Anonymous" } { key } if$ duplicate$ }
            { organization duplicate$ }
          if$
        }
        { editor format.lab.names editor my.full.label }
      if$
    }
    { author format.lab.names author my.full.label }
  if$
  % POP: Save the abbreviated label separately: different long author lists
  % can both cite as Smith et al. and still need distinct year suffixes.
  swap$ duplicate$ 'label.short := swap$
  "}{" * swap$ * "}{" *
  year empty$ { "n.d." } { year } if$ 'label.year :=
}

% POP: Head fallback mirrors calc.label, so printed entries and citations agree.
FUNCTION {format.head}
{ author empty$
    { editor empty$
        { organization empty$
            { key empty$ { "Anonymous" } { key } if$ }
            { organization bold.names }
          if$
        }
        { format.editors }
      if$
    }
    { format.authors }
  if$
}

FUNCTION {output.bibitem}
{ newline$

  "\bibitem[\protect\citeauthoryear{" write$
  calc.label write$
  sort.year write$
  "}]{" write$

  cite$ write$
  "}" write$
  newline$
  ""
  before.all 'output.state :=
}

% POP: Article metadata; absent volume/issue/pages is valid for advance publication.
FUNCTION {article}
{ output.bibitem format.head output output.year.check
  new.block format.title "title" output.check
  new.block format.jour.vol output
  new.block note output fin.entry
}

% POP: Book head/title, optional volume/series, City: Publisher, then note and electronic links.
FUNCTION {book}
{ output.bibitem format.head output output.year.check
  new.block format.btitle "title" output.check
  format.bvolume output format.number.series output
  new.block address output publisher "publisher" output.check.colon
  new.block note output fin.entry
}

FUNCTION {booklet}
{ output.bibitem format.head output output.year.check
  new.block format.title "title" output.check
  new.block howpublished output address output
  new.block note output fin.entry
}

FUNCTION {inbook}
{ output.bibitem format.head output output.year.check
  new.block format.btitle "title" output.check
  format.bvolume output format.number.series output
  format.chapter.pages output
  new.block address output publisher "publisher" output.check.colon
  new.block note output fin.entry
}

% POP: Full chapter/container citation; inherited crossref fields do not emit a separate See citation.
FUNCTION {incollection}
{ output.bibitem format.head output output.year.check
  new.block format.title "title" output.check
  new.block format.in.ed.booktitle "booktitle" output.check
  format.bvolume output format.number.series output
  format.chapter.pages output
  new.block address output publisher output.colon
  new.block note output fin.entry
}

% POP: Conference papers follow the same title/container/editor/page order as chapters.
FUNCTION {inproceedings}
{ incollection }

FUNCTION {conference} { inproceedings }

FUNCTION {manual}
{ output.bibitem format.head output output.year.check
  new.block format.btitle "title" output.check
  new.block address output
  publisher empty$ { organization output.colon } { publisher output.colon } if$
  new.block note output fin.entry
}

FUNCTION {mastersthesis}
{ output.bibitem format.head output output.year.check
  new.block format.title "title" output.check
  new.block "Master's thesis" format.thesis.type output
  school "school" output.check address output
  new.block note output fin.entry
}

FUNCTION {misc}
{ output.bibitem format.head output output.year.check
  new.block format.title output
  new.block howpublished output
  new.block note output fin.entry
}

% POP: Common export aliases; all three use ordinary BibTeX year/title/url fields.
FUNCTION {online} { misc }
FUNCTION {electronic} { misc }
FUNCTION {preprint} { misc }

FUNCTION {phdthesis}
{ output.bibitem format.head output output.year.check
  new.block format.title "title" output.check
  new.block "PhD thesis" format.thesis.type output
  school "school" output.check address output
  new.block note output fin.entry
}

FUNCTION {proceedings}
{ output.bibitem format.head output output.year.check
  new.block format.btitle "title" output.check
  format.bvolume output format.number.series output
  new.block address output publisher output.colon
  new.block note output fin.entry
}

FUNCTION {techreport}
{ output.bibitem format.head output output.year.check
  new.block format.title "title" output.check
  new.block format.tr.number output
  institution "institution" output.check address output
  new.block note output fin.entry
}

% POP: Notes are optional: a URL/eprint may fully identify an unpublished paper.
FUNCTION {unpublished}
{ output.bibitem format.head output output.year.check
  new.block format.title "title" output.check
  new.block note output fin.entry
}

FUNCTION {default.type} { misc }

MACRO {jan} {"January"}

MACRO {feb} {"February"}

MACRO {mar} {"March"}

MACRO {apr} {"April"}

MACRO {may} {"May"}

MACRO {jun} {"June"}

MACRO {jul} {"July"}

MACRO {aug} {"August"}

MACRO {sep} {"September"}

MACRO {oct} {"October"}

MACRO {nov} {"November"}

MACRO {dec} {"December"}

MACRO {acmcs} {"ACM Computing Surveys"}

MACRO {acta} {"Acta Informatica"}

MACRO {ai} {"Artificial Intelligence"}

MACRO {cacm} {"Communications of the ACM"}

MACRO {ibmjrd} {"IBM Journal of Research and Development"}

MACRO {ibmsj} {"IBM Systems Journal"}

MACRO {ieeese} {"IEEE Transactions on Software Engineering"}

MACRO {ieeetc} {"IEEE Transactions on Computers"}

MACRO {ieeetcad}
 {"IEEE Transactions on Computer-Aided Design of Integrated Circuits"}

MACRO {ipl} {"Information Processing Letters"}

MACRO {jacm} {"Journal of the ACM"}

MACRO {jcss} {"Journal of Computer and System Sciences"}

MACRO {scp} {"Science of Computer Programming"}

MACRO {sicomp} {"SIAM Journal on Computing"}

MACRO {tocs} {"ACM Transactions on Computer Systems"}

MACRO {tods} {"ACM Transactions on Database Systems"}

MACRO {tog} {"ACM Transactions on Graphics"}

MACRO {toms} {"ACM Transactions on Mathematical Software"}

MACRO {toois} {"ACM Transactions on Office Information Systems"}

MACRO {toplas} {"ACM Transactions on Programming Languages and Systems"}

MACRO {tcs} {"Theoretical Computer Science"}

READ

FUNCTION {sortify}
{ purify$
  "l" change.case$
}

INTEGERS { len }

FUNCTION {chop.word}
{ 's :=
  'len :=
  s #1 len substring$ =
    { s len #1 + global.max$ substring$ }
    's
  if$
}



% POP: Alphabetize by full given names, not only their initials.
FUNCTION {sort.format.names}
{ 's :=
  #1 'nameptr :=
  ""
  s num.names$ 'numnames :=
  numnames 'namesleft :=
    { namesleft #0 > }
    { nameptr #1 >
          { "   " * }
         'skip$
      if$
      s nameptr "{vv{ } }{ll{ }}{  ff{ }}{  jj{ }}" format.name$ 't :=
      nameptr numnames = t "others" = and
          { " et~al" * }
          { t sortify * }
      if$
      nameptr #1 + 'nameptr :=
      namesleft #1 - 'namesleft :=
    }
  while$
}

FUNCTION {sort.format.title}
{ 't :=
  "A " #2
    "An " #3
      "The " #4 t chop.word
    chop.word
  chop.word
  sortify
  #1 global.max$ substring$
}

FUNCTION {author.sort}
{ author empty$
    { key empty$
         { "to sort, need author or key in " cite$ * warning$
           "" }
         { key sortify }
      if$
    }
    { author sort.format.names }
  if$
}

FUNCTION {editor.sort}
{ editor empty$
    { key empty$
         { "to sort, need editor or key in " cite$ * warning$
           ""
         }
         { key sortify }
      if$
    }
    { editor sort.format.names }
  if$
}

FUNCTION {author.editor.sort}
{ author empty$
    { "missing author in " cite$ * warning$
      editor empty$
         { key empty$
             { "to sort, need author, editor, or key in " cite$ * warning$
               ""
             }
             { key sortify }
           if$
         }
         { editor sort.format.names }
      if$
    }
    { author sort.format.names }
  if$
}

FUNCTION {author.organization.sort}
%
% added - GNP. Stack author or organization for sorting (from alpha.bst).
% Unlike alpha.bst, we need entire names, not abbreviations
%
{ author empty$
    { organization empty$
	{ key empty$
	    { "to sort, need author, organization, or key in " cite$ * warning$
	      ""
	    }
	    { key sortify }
	  if$
	}
	{ organization sortify }
      if$
    }
    { author sort.format.names }
  if$
}

FUNCTION {editor.organization.sort}
%
% added - GNP. Stack editor or organization for sorting (from alpha.bst).
% Unlike alpha.bst, we need entire names, not abbreviations
%
{ editor empty$
    { organization empty$
	{ key empty$
	    { "to sort, need editor, organization, or key in " cite$ * warning$
	      ""
	    }
	    { key sortify }
	  if$
	}
	{ organization sortify }
      if$
    }
    { editor sort.format.names }
  if$
}

% POP: Save the full-name sort order for the final bibliography. First group
% equal abbreviated citation labels/years together (including et al.), then
% allocate a/b suffixes by full names/title. Final bib.sort.order restores
% alphabetical full names, year, title ordering.
FUNCTION {presort}
{ calc.label pop$ label.short 'u :=
  author empty$
    { editor empty$
        { organization empty$
            { key empty$ { "anonymous" } { key sortify } if$ }
            { organization sortify }
          if$
        }
        { editor sort.format.names }
      if$
    }
    { author sort.format.names }
  if$
  #1 entry.max$ substring$ 'sort.label :=
  u label.year * "    " * sort.label * "    " *
  title field.or.null sort.format.title *
  #1 entry.max$ substring$ 'sort.key$ :=
}

ITERATE {presort}

SORT             % by label, year, author/editor, title

STRINGS { last.label next.extra }

INTEGERS { last.extra.num suffix.number suffix.quotient suffix.remainder }
STRINGS { suffix.text }

% POP: Positive ordinal -> a..z, aa..az, ba..bz, ..., zz, aaa, ... .
% BibTeX has no integer division primitive; repeated subtraction supplies the
% quotient/remainder for bijective base 26. Never emit ASCII punctuation as a
% year suffix: braces would corrupt the natbib optional argument and fail TeX.
FUNCTION {pop.alpha.suffix}
{ 'suffix.number :=
  "" 'suffix.text :=
  { suffix.number #0 > }
  { suffix.number #1 - 'suffix.remainder :=
    #0 'suffix.quotient :=
    { suffix.remainder #25 > }
    { suffix.remainder #26 - 'suffix.remainder :=
      suffix.quotient #1 + 'suffix.quotient :=
    }
    while$
    suffix.remainder "a" chr.to.int$ + int.to.chr$
    suffix.text * 'suffix.text :=
    suffix.quotient 'suffix.number :=
  }
  while$
  suffix.text
}

FUNCTION {initialize.extra.label.stuff}
{ #0 int.to.chr$ 'last.label :=
  "" 'next.extra :=
  #0 'last.extra.num :=
}

FUNCTION {forward.pass}
%
% Pass through all entries, comparing current entry to last one.
% Need to concatenate year to the stack (done by calc.label) to determine
% if two entries are the same (see presort)
%
{ last.label
  calc.label pop$ label.short label.year * % POP: short citation label and full year.
  #1 entry.max$ substring$ =     % are they equal?
     { last.extra.num #1 + 'last.extra.num :=
       last.extra.num pop.alpha.suffix 'extra.label :=
     }
     { #1 'last.extra.num :=
       "" 'extra.label :=
       calc.label pop$ label.short label.year * % POP: short citation label and full year.
       #1 entry.max$ substring$ 'last.label := % assign to last.label
     }
  if$
}

FUNCTION {reverse.pass}
{ next.extra "b" =
    { "a" 'extra.label := }
     'skip$
  if$
  % Natbib reads the suffix as one TeX argument after a four-digit year.
  % Group multi-letter suffixes so compressed citations retain aa/ab/etc.
  label.year
  extra.label text.length$ #1 >
    { "{" extra.label * "}" * }
    { extra.label }
  if$
  * 'sort.year :=
  extra.label 'next.extra :=
}

EXECUTE {initialize.extra.label.stuff}

ITERATE {forward.pass}

REVERSE {reverse.pass}

FUNCTION {bib.sort.order}
{ sort.label
  "    "
  *
  year field.or.null sortify
  *
  "    "
  *
  title field.or.null
  sort.format.title
  *
  #1 entry.max$ substring$
  'sort.key$ :=
}

ITERATE {bib.sort.order}

SORT             % by sort.label, year, title --- giving final bib. order.

FUNCTION {begin.bib}

{ preamble$ empty$
    'skip$
    { preamble$ write$ newline$ }
  if$
  "\begin{thebibliography}{}" write$ newline$
  % POP: Match the publisher's regular text face for links, locally to this list.
  "\urlstyle{same}" write$ newline$
}


EXECUTE {begin.bib}

EXECUTE {init.state.consts}

ITERATE {call.type$}

FUNCTION {end.bib}
{ newline$
  "\end{thebibliography}" write$ newline$
}

EXECUTE {end.bib}