make best practises: parentheses for variable names

[Robert P. J. Day]

  i want to write a short coding standards doc for writing makefiles
for a few people who know even less about makefiles than i do, and one
of the things i'd like to enforce is the use of ${VARNAME} rather than
$(VARNAME) when referring to variables.

  i just want to clarify that those two uses are exactly equivalent,
yes?  i prefer the first form since it matches variable usage in the
unix shell, while the second resembles command substitution, and i'd
rather keep things vaguely consistent.

  comments?  is there a good online doc for "best practises"
somewhere?

rday