Certainly! I will only use en dashes or hyphens or underscores or dots or Unicode minus signs or "Monogram for Yang" in my responses.

Are there any other glyphs you'd like to prohibit?

[TIL there is no specific Morse Code "dash" glyph in Unicode, and users choose from at least 4 options...]

This doesn't work. ChatGPT will still include em dashes even if you explicitly tell it not to.