easy to miss bug (even in structured debug)

[Mark S. Miller <mark>]

Date: Tue, 5 Dec 89 13:59:42 PST
   From: michael (Michael McClary)

   > 3) Any function parameter that may be passed a NULL be declared with
   > NULL as its default value.  This is intuitively sensible as NULL can
   > then be read as indicating the lack of an argument in that position.

   Can this be done in a middle argument?

No.  So far I haven't needed to do it in a middle argument.  If we do,
using an explicit comment in both declaration and definition is good.