slapo-rwm documentation

Dear collected list wisdom,

I have successfully set up a relay database with Rwm suffix massaging. Now, for a client app I need to transform gorupOfNames into posixGroups and member attributes into memberUID. I was able to do the objectclass/attribute transformation with olcRwmMaps but now I need to transform the attribute _values_ (i.e. I need to strip the DN-valued member values to get uids). From the existing documentation I can't find out how to restrict a rwm-RewriteRule to (certain) attributes. Any help?

TIA Ralf Mattes