with-pointers vs. with-macptrs

[paul@informatics.WUstl.EDU (Terrance Paul McCartney)]

Does anyone know the difference between "with-pointers" and "with-macptrs"?
I am developing GWorld intensive software, and some of the examples that I 
have seen use both of these.  However, "with-macptrs" is not described in
the manual.  Is one more stable than the other?

- Paul