cetaapana/cetaapanna

Dear Ole,

Could you maybe explain the variation between cetaapanna and cetaapana.
All editions and mss of the Suttavibhan.ga and Paatimokkha I have
consulted, except the Thai printed ones, read cetaapanna (as part the
compound ciivaracetaapanna) in Nissaggiya Paacittiya rule 8-10.

Cetaapana is an action-noun and as part of the cpd (which I take as a
dative tappurisa) it means: ''exchange-fund for a robe''. Another monk
suggested that cetaapanna could be an adjective that has come about by
cetaapana + ya > cetaapanya > cetaapanna in line with
kammaniya/kamma~n~na. However, then cetaapa~n~na would be expected and
it would make the compound a bahubbihi (''exchangeable for a robe'')
that would need to qualify a noun, which is not found here.

Regards,
                     Bh. Nyanatusita