So the correct statement is more like:

Blocks have IDs that are unique within a document.

A document version + block ID can identify a block within a specific document version, but the code does not model the block ID itself as version/block-id.

The URL/reference format is:

hm://account/path?v=version#block-id

Example from tests:

hm://123?v=foo#bar

So:

version = document version query param, ?v=foo
block-id = fragment/block ref, #bar
revision = separate block field: last Change that modified the block

Better wording:

A block is addressed as document ID + optional document version + blockRef. Block IDs are unique within a document, not encoded as version/block-id.

Recap

“Blocks have unique IDs: version/block-id” is not quite correct.