Look, I get that overlay syntaxes are inherently subject to this sort of
confusion. It's why got rid of all of them from MIME in the transition from
1521 to RFCs 2045 and 2046. The diffference is in MIME the overlay syntaxes
turned out not to be essentially useless. THis is not the case in Sieve.
Correction: I meant to say "turned out to be essentally useless".
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