Thanks to Kuroneko for a solution to the LMM flag problem.

The Parallax forum user Kuroneko posted a solution to my problem with flag setting intruction when using LMM.

Here is his solution:

set_z_c   cmpsub  0, 0 wz,wc,nr
set_z_nc  neg     0, #0 wz,wc,nr
set_nz_nc neg     0, #1 wz,wc,nr

set_nz_c  cmp     reg, #1 wz,wc  ' reg holding NULL, e.g. par
          cmpsub  reg, #0 wz,wc  ' reg holding non-NULL value

Now I just need to implement these and post a new version of PropBasic.

Bean