Defining Label Environments
===========================

 - User Option: reftex-default-label-alist-entries
     Default label alist specifications.  It is a list of symbols with
     associations in the constant `reftex-label-alist-builtin'.
     `LaTeX' should always be the last entry.

 - User Option: reftex-label-alist
     Set this variable to define additions and changes to the defaults
     in `reftex-default-label-alist-entries'.  The only things you
     *must not* change is that `?s' is the type indicator for section
     labels, and <SPC> for the `any' label type.  These are hard-coded
     at other places in the code.

     The value of the variable must be a list of items.  Each item is a
     list itself and has the following structure:

           (ENV-OR-MACRO  TYPE-KEY  LABEL-PREFIX  REFERENCE-FORMAT
              CONTEXT-METHOD  (MAGIC-WORD ... ))

     Each list entry describes either an environment carrying a counter
     for use with `\label' and `\ref', or a LaTeX macro defining a
     label as (or inside) one of its arguments.  The elements of each
     list entry are:

    ENV-OR-MACRO
          Name of the environment (like `table') or macro (like
          `\myfig').  For macros, indicate the arguments, as in
          `\myfig[]{}{}{*}{}'.  Use square brackets for optional
          arguments, a star to mark the label argument, if any.  The
          macro does not have to have a label argument - you could also
          use `\label{...}' inside one of its arguments.

          Special names: `section' for section labels, `any' to define a
          group which contains all labels.

          This may also be `nil' if the entry is only meant to change
          some settings associated with the type indicator character
          (see below).

    TYPE-KEY
          Type indicator character, like `?t', must be a printable ASCII
          character.  The type indicator is a single character which
          defines a label type.  Any label inside the environment or
          macro is assumed to belong to this type.  The same character
          may occur several times in this list, to cover cases in which
          different environments carry the same label type (like
          `equation' and `eqnarray').  If the type indicator is `nil'
          and the macro has a label argument `{*}', the macro defines
          neutral labels just like `\label'.  In this case the reminder
          of this entry is ignored.

    LABEL-PREFIX
          Label prefix string, like `tab:'.  The prefix is a short
          string used as the start of a label.  It may be the empty
          string.  The prefix may contain the following `%' escapes:

               %f Current file name, directory and extension stripped.
               %F Current file name relative to master file directory.
               %u User login name, on systems which support this.

          Example: In a file `intro.tex', `eq:%f:' will become
          `eq:intro:'.

    REFERENCE-FORMAT
          Format string for reference insert in buffer.  `%s' will be
          replaced by the label.  When the format starts with `~', this
          `~' will only be inserted when the character before point is
          *not* a whitespace.

    CONTEXT-METHOD
          Indication on how to find the short context.
             - If `nil', use the text following the `\label{...}' macro.

             - If `t', use
                  - the section heading for section labels.

                  - text following the `\begin{...}' statement of
                    environments (not a good choice for environments
                    like eqnarray or enumerate, where one has several
                    labels in a single environment).

                  - text after the macro name (starting with the first
                    arg) for macros.

             - If an integer, use the nth argument of the macro.  As a
               special case, 1000 means to get text after the last
               macro argument.

             - If a string, use as regexp to search *backward* from the
               label.  Context is then the text following the end of
               the match.  E.g. putting this to `\\caption[[{]' will
               use the caption in a figure or table environment.
               `\\begin{eqnarray}\|\\\\' works for eqnarrays.

             - If any of `caption', `item', `eqnarray-like',
               `alignat-like', this symbol will internally be
               translated into an appropriate regexp (see also the
               variable `reftex-default-context-regexps').

             - If a function, call this function with the name of the
               environment/macro as argument.  On call, point will be
               just after the `\label' macro.  The function is expected
               to return a suitable context string.  It should throw an
               exception (error) when failing to find context.  As an
               example, here is a function returning the 10 chars
               following the label macro as context:

                    (defun my-context-function (env-or-mac)
                       (if (> (point-max) (+ 10 (point)))
                           (buffer-substring (point) (+ 10 (point)))
                         (error "Buffer too small")))

          Label context is used in two ways by RefTeX: For display in
          the label menu, and to derive a label string.  If you want to
          use a different method for each of these, specify them as a
          dotted pair.  E.g. `(nil . t)' uses the text after the label
          (`nil') for display, and text from the default position (`t')
          to derive a label string.  This is actually used for section
          labels.

    MAGIC-WORD-LIST
          List of magic words which identify a reference to be of this
          type.  If the word before point is equal to one of these
          words when calling `reftex-reference', the label list offered
          will be automatically restricted to labels of the correct
          type.  If the first element of this word-list is the symbol
          `regexp', the strings are interpreted as regular
          expressions(1).

     If the type indicator characters of two or more entries are the
     same, RefTeX will use
        - the first non-`nil' format and prefix

        - the magic words of all involved entries.

     Any list entry may also be a symbol.  If that has an association in
     `reftex-label-alist-builtin', the `cddr' of that association is
     spliced into the list.  However, builtin defaults should normally
     be set with the variable `reftex-default-label-alist-entries'.

 - User Option: reftex-section-levels
     Commands and levels used for defining sections in the document.
     The `car' of each cons cell is the name of the section macro.  The
     `cdr' is a number indicating its level.  A negative level means the
     same as the positive value, but the section will never get a
     number.

 - User Option: reftex-default-context-regexps
     Alist with default regular expressions for finding context.  The
     emacs lisp form `(format regexp (regexp-quote environment))' is
     used to calculate the final regular expression - so `%s' will be
     replaced with the environment or macro.

   ---------- Footnotes ----------

   (1) Careful:  RefTeX will add stuff to the beginning and end of
these regular expressions.