Upper limit of a string
Sorry if this is answered somewhere in the docs, I can't seem to find anything that matches the exact thing I'm looking for.
I have a value that is a NULL-terminated string but can be no longer than 256 bytes (with NULL terminator included). I tried doing:
```ksy
      - id: name
        type: strz
        size: 256
        encoding: ASCII
```
but this seems to imply that the string *is* 256 bytes, not that the maximum is 256 bytes. This doesn't work for me since the field size depends on where the null-terminator is or if it reaches 256 bytes.
Is there anything that can describe what I'm wanting?

EDIT: It would also work if there was maybe an error that occurred if the null-terminator was past the 256-byte mark.