XML Link is used in a few places, for example the PeopleSoft Finance Journal Upload process. It is part of Business Interlinks.
You can test Business Interlinks from PeopleTools > Utilities > Debug > PeopleTools Test Utilities
PeopleTools > Utilities > Administration > XML Link Function Registry
For PeopleSoft Finance Journal Upload Process:
- Service = Excel_Journal_Import
Check users have access to WEBLIB_XMLLINK (PSAUTHWEBLIBVW) and WEBLIB_GL