>I think we're confusing "pre-processing" and "compiling"; these are simply "code substitutions" performed during the pre-processor stage. The substituted code (ie. .... SYS( n ) ....) is what is getting compiled.

Here's another good example for this:

#DEFINE ccMESSAGE0 "Hello Mike!"
#DEFINE ccMESSAGE1 Hello Mike!
#DEFINE ccMESSAGE2 UPPER('Hello Mike!')
#DEFINE ccMESSAGE3 ('Hello Mike!')
?ccMESSAGE0
?[ccMESSAGE1]
?ccMESSAGE2
?UPPER ccMESSAGE3