TAP is an alternative protocol specification for a successor to RFC931
that Pidentd is compatible with. TAP is a more "clean" protocol and
doesn't include as many new "features" as IDENT does, but the basic 
functionality is more or less the same. If you don't use the extra
features of the IDENT protocol (which has to be explicitly enabled in
Pidentd), then it should be compatible.
 
/Peter Eriksson <pen@lysator.liu.se>