Does display_name field get filtered in User API?

[wjones20]

Hello,

Does anyone know if the User API field for display_name get filtered against a list of disallowed names?  We have a preferred name process that uses the display_name field, but a preferred name change that we sent over in first_name and display_name only showed up in the Full Name and Sortable Name fields in the user file. The preferred name failed to go through in the display_name field. Hundreds of other preferred names have gone over without interruption.

Thanks,

Bill