(tds.info)Portable filenames

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A.1 Portable filenames
======================

The TDS cannot require any particular restriction on filenames in the
tree, since the names of many existing TeX files conform to no standard
scheme. For the benefit of people who wish to make a portable TeX
distribution or installation, however, we outline here the necessary
restrictions. The TDS specifications themselves are compatible with
these.

   ISO-9660 is the only universally acceptable file system format for
CD-ROMs.  A subset thereof meets the stringent limitations of all
operating systems in use today. It specifies the following:

   * File and directory names, not including any directory path or
     extension part, may not exceed eight characters.

   * Filenames may have a single extension.  Extensions may not exceed
     three characters. Directory names may not have an extension.

   * Names and extensions may consist of _only_ the characters `A'-`Z',
     `0'-`9', and underscore.  Lowercase letters are excluded.

   * A period separates the filename from the extension and is always
     present, even if the name or extension is missing (e.g.,
     `FILENAME.' or `.EXT').

   * A version number, ranging from 1-32767, is appended to the file
     extension, separated by a semicolon (e.g., `FILENAME.EXT;1').

   * Only eight directory levels are allowed, including the top-level
     (mounted) directory (see Section Note: Rooting the tree).  Thus,
     the deepest valid ISO-9660 path is:
          texmf/L2/L3/L4/L5/L6/L7/L8/FOO.BAR;1
          1     2  3  4  5  6  7  8
     The deepest TDS path needs only seven levels:
          texmf/fonts/pk/cx/public/cm/dpi300/cmr10.pk
          1     2     3  4  5      6  7


   Some systems display a modified format of ISO-9660 names, mapping
alphabetic characters to lowercase, removing version numbers and
trailing periods, etc.

   Before the December 1996 release, LaTeX used mixed-case names for
font descriptor files.  Fortunately, it never relied on case alone to
distinguish among the files.  Nowadays, it uses only monocase names.