Question

[madhav.deshpande at um.cc.umich.edu]

        In pre-modern Maharashtra, there was a tradition that the education
of a child would begin with the words ONAAMAASIIDHAM, which is a vernacular
form for "om namah siddham."  The child would be introduced to the alphabet
after this.  This tradition is mentioned in some old Marathi Jain works
as well.
        Does anyone know of a Sanskrit grammatical text which begins with
this formula?  The Kaatantra begins with "siddho varNasamaamnaayah".  But
where does "om namah siddham" come from?
        Madhav Deshpande