What characters may be included in instagram's shortcode?

Question

I want to validate user's input. Maybe, someones know what characters can be included in shortcode?

I have checked Instagram's documentation, but haven't found any information regarding it.

For example in pinterest's documentation there is information about shortcode:

Creates a logging tag for analytics. Tags may include the characters a-z, A-Z, 0-9 and underscore, and are constrained to 32 characters.

Answer 1

These are valid: a-z A-Z 0-9 _ -