tds: Portable filenames

 
 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 ⇒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.