> While the application *can* get N by querying the charset system table,

Why application ? It is job of data access layer\components.

> it is a rather complicated task

Really ???

> and also not very intuitive that it is required.

Do you consider "too complex and not very intuitive" for data access layer
to query system tables for fileds CHECK constraints, DEFAULT values, etc ?

Regards,
Vlad

PS You trying to make elephant from the fly (old russian proverb) ;)