In reply to dave_59:
In my case DISABLE is a parameter.
bins mode_a = {3'b100};
illegal_bins no_a = {3'b100} with (DISABLE);
does not compile and I get an error.
In the method I’m using (iff), both coverpoints get triggered but the illegal_bin only get triggered if the iff is true, so the value goes into the illegal_bin and the normal bin then becomes an illegal_bin. Is there a specific reason that it doesn’t do the same for transition bins or is it just the limited functionality?