relative + demonstrative pronoun compound; nom. sg. masc. or neut. (assuming standard text is 'yo ayaṁ'; surface form 'yvāyaṁ' appears to be a contraction or scribal variant)
Analysis. yo (relative pronoun, 'who') + ayaṁ (demonstrative pronoun, 'this'); compounds to form 'this one who', common in conditional or identifying formulas
Meanings from the Digital Pāḷi Dictionary; morphology and etymology by Claude.
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