OLC - How does the Person number list with type as TEXT will work for creating Assignments

Summary:

Wanted to know when we assign learners using Person number list with type as TEXT, what is the exact format which we need to use, where it ask for "Filename or URL". What we need to provide in this field and how it will work.

Content (please ensure you mask any confidential information):

We assigned the learners using Person number list with type as TEXT and in the field "Filename or URL" we entered the person numbers one after the other as mentioned below in screenshot and it worked and created the assignments but it took only few learners from most of the learners(missed few learners),