Proviso scope: limits exceptions to the subject matter, to be read with the main enactment for harmonious construction. A proviso functions as a conditional exception or limitation appended to an enacting clause and must be read in relation to the principal matter it qualifies. It is not an independent enactment and should be confined to the subject matter of the enacting clause, construed so that proviso and main text mutually illuminate each other. Where the main enactment is clear, a proviso cannot be employed to exclude or nullify what falls within the express terms of the principal clause.