Do screenwriters use pen names?

Do screenwriters use pen names? A writer must use his/her own name in all writing credits unless he/she has already established a pseudonym or registers one at the Guild office before commencement of employment on a writing assignment, or before disposition of any rights to literary material on which he/she wishes to use such pseudonym.

A writer must use his/her own name in all writing credits unless he/she has already established a pseudonym or registers one at the Guild office before commencement of employment on a writing assignment, or before disposition of any rights to literary material on which he/she wishes to use such pseudonym.