[grogers]

Other than ASN.1 PER, is there any other widely used encoding format that isn't self-describing? Using TLV certainly adds flexibility around schema evolution, but I feel like collectively we are wasting a fair amount of bytes because of it...

[tliltocatl]

Cap'n'proto doesn't have tags, but it wastes even more bytes in favor of speed. Than again, omitting tags only saves space if you are sending all the fields every time. PER uses a bitmap, which is still a bit wasteful on large sparse structs.

[cryptonector]

PER sends a bitmap only of OPTIONAL members' (fields') presence/absence. Required members are just where you expect them: right after their preceding members.

[cryptonector]

Also JSOON and XML are not TLV, though of course they're not really good examples of non-TLV encodings -- certainly they can't be what you had in mind.

[cryptonector]

OER (related to PER)

XDR (ONC RPC, NFS)

MS RPC (DCE RPC w/ tweaks)

Flat Buffers