hyppo_readdir insufficiently documented

[M3wP]

Describe where we can find the problematic topic
Appendix N Hyppo services, hyppo_readdir

Describe the solution you'd like
The description of the directory entry should be correct. There ARE NULL bytes where it says there aren't any. In fact, there are two. $4D and $4E should be marked as either reserved or NULL.

Describe alternatives you've considered

Additional context