You wrote:
<< The final question appears to me to be asking, what is the purpose
of (definging) the word 'syllable' (akkhara). I.e. why bother defining
it here? The answer is a reference to sutta 1, which employs the term
'syllable'. A similar formula is used in a number of the following
suttas, and amounts to a kind of cross-referencing system. I'm
reading with the PED as kvattho = ko attho but wonder if it might be
kva + attho? >>
Under the article "Kaccaayana-vyaakara.na" in Malalasekera's DPPN,
there is mention of a payoga portion (grammatical analyses with
examples) for the sutta in addition to a vutti portion (or
supplements, to render the sutta intelligible). I take it that the
following makes up the payoga portion:
and everything before this is the vutti portion except for the sutta
itself. This demonstrates an application of rule 2. Rule 1 is cited
merely because it contains the word 'akkhara-' and any other rule
containing that word would have been okay too, eg. 604/606 akkharehi
kaara.
I think kvattho = ko attho. Also, 'application' would be a more
helpful rendering than 'purpose'.