Int 21 Fn 13  - DOS 1+ - Delete File Using Fcb                             [D]

   AH = 13h
   DS:DX -> unopened FCB (see AH=0Fh), filename filled with template for
       deletion ('?' wildcards allowed)

Return: AL = status
       00h one or more files successfully deleted
       FFh no matching files or all were read-only or locked

Notes: DOS 1.25+ deletes everything in the current directory (including
     subdirectories) and sets the first byte of the name to 00h (entry
     never used) instead of E5h if called on an extended FCB with
     filename '???????????' and bits 0-4 of the attribute set (bits 1 and
     2 for DOS 1.x).  This may have originally been an optimization to
     minimize directory searching after a mass deletion (DOS 1.25+ stop
     the directory search upon encountering a never-used entry), but can
     corrupt the filesystem under DOS 2+ because subdirectories are
     removed without deleting the files they contain.
   currently-open files should not be deleted
   MS-DOS allows deletion of read-only files with an extended FCB, whereas
     Novell NetWare does not

See Also: AH=41h,INT 2F/AX=1113h