For block length, if you can't use context or control character/symbols, then the label would be required to specific the length of the payload in bytes, or sim

For block length, if you can't use context or control character/symbols, then the label would be required to specific the length of the payload in bytes, or similar. When you reach the end of the given length, then the next token should be the closing payload tag/brace. The important thing here is that everything gets described. The structures within a field, such as label, meta, validators, etc. always follow the specification set by the previous label. That label then sets the specifications for the next payload. And since the validators and such are Turing complete, the specifications can be anything, rebuilt within dit schemas.