`.comm SYMBOL , LENGTH '
========================

   `.comm' declares a named common area in the bss section.  Normally
`ld' reserves memory addresses for it during linking, so no partial
program defines the location of the symbol.  Use `.comm' to tell `ld'
that it must be at least LENGTH bytes long.  `ld' will allocate space
for each `.comm' symbol that is at least as long as the longest `.comm'
request in any of the partial programs linked.  LENGTH is an absolute
expression.