I mean, really, why would it be encrypted?

[bi3mw]

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Friedman did not really say that it is not a cipher. This would require a definition of 'cipher'.
He did say that it looked more like an early form of synthetic language.

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After all, the construction of a language would make its application to the whole manuscript seem plausible. But even Hildegard von Bingen has explained her Lingua Ignota and only used in hymns. The VMS either lacks the companion volume or it is intended that nobody should be able to read the content. The latter can be assumed, since there is obviously no explanatory plain text in the VMS. No side note, nothing.  If it is a constructed language, then the author(s), in contrast to Hildegard von Bingen, only wanted to apply his method and not introduce it.