These structs are a lossless projection of the binary `.ptwm` wire format. Every field needed to reconstruct the container byte-for-byte is captured; large/opaque binaries (compressed plane payloads, externalized codec state, embedded modules) are referenced by member key and live outside the JSON. The schema restricts scalars to integers, strings, booleans, and `null`; opaque byte fields are carried as base64 (`*_b64`). See [`super::jcs`] for the canonicalization that makes manifest hashes reproducible.