If you are in doubt you can always perform a little test.
I made a simple table with Name and Category fields.
Then I related that to another occurrence of itself using the category field.
Then I created some records and assigned some categories. Some contacts had multiple categories.
I did this by making the categorie field a checkbox set. But also put the category field on the layout a second time, but as an edit box. So I could see the values showing up in that field.
As you check more values you will see they all show up in the edit box on multiple lines. Separated by a return.
So if you check "Student", "Teacher", and "Relative" you get:
in your edit box.
Now, in your portal that's showing related records you will see that all contacts that share a category are shown.
So filemaker evaluates every line in the category field seperately.
Have a look at the file.
So the answer to your question is "Yes" That works.