I just got rather badly burned by not realising that ADD_CRE_EFFECT doesn't work for v1 EFF files.
RTFM is a pretty reasonable response, since it is documented, but any chance this could at least be turned into an explicit FAIL? (i.e., if you try to use ADD_CRE_EFFECT on a wrong-effect creature, the install fails). That should take very little time to code and would prevent other people making my mistake. At the moment, the macro silently and fatally breaks v0 creatures when you use it on them. I'm probably not the only person who tends to work out the syntax of WEIDU commands at least in part from context, and who doesn't always do their homework.