do-backs
Integrity protected container, analogue to ASN.1-based CMS DigestedData.
=> https://datatracker.ietf.org/doc/html/rfc5652.html CMS

Stored in a file, it should begin with "cm/hashed" [encoding/MAGIC].

<<    [schemas/hashed.tcl]

It is just a single map of algorithm identifiers with hashes.

Hashed data is provided any way you wish. Consider using "prehash"
structure similarly as [cm/signed/] does:

<<    [schemas/prehash.tcl]

    prehash || BLOB(data) || cm/hashed
