John Kelly wrote:

> Also,
> experience has shown me that the prefix pa.ti- often is changed to
> pacca- (I'm not sure why this happens or if there is any rule as to
> when this change is made - perhaps somehow more knowledgable on the
> list can help).

I think this might be a "doh !" moment. Pacca- is almost always a
contracted form of pa.ti- before an "a" or "aa" (= Skt "praty + a).
Similary, "paccu" is a contracted form of pat.ti before an "u". There is
even an entry to this effect in PED.

Best wishes,
Stephen Hodge