filename.  The 'N_EINCL' value,
and the values of the other and description fields for all three, appear
to always be zero.

   For the start of an include file in XCOFF, use the '.bi' assembler
directive, which generates a 'C_BINCL' symbol.  A '.ei' directive, which
generates a 'C_EINCL' symbol, denotes the end of the include file.  Both
directives are followed by the name of the source file in quotes, which
becomes the string for the symbol.  The value of each symbol, produced
automatically by the assembler and linker, is the offset into the
executable of the beginning (inclusive, as you'd expect) or end
(inclusive, as you would not expect) of the portion of the COFF line
table that corresponds to this include file.  'C_BINCL' and 'C_EINCL' do
not nest.