Maximum number of values in an enum constraint

Frictionless Data
1

In a table schema, what would be a reasonable maximum number of values to place in an enum constraint before it made more sense to create a foreign key relationship to a reference table?

For context, I’m planning to implement features to create an enum constraint from a column and create a reference table from a column.

2

Just saw Bootstrapping data standards with Frictionless Data that discusses data packages for domain specific data standards. In the 360Giving data package the currency field has an enum constraint with 163 constraint values.