We have a custom tab created for item revision where the users enter item revision and the related data. The requirement is to get the active revision number from there and update the header field called ‘Current Revision’ on the item, this is another custom field. I have tried defaulting on the field setup but it does not give me an option to go through this custom record for the item and pick the value of revision where inactive is ‘No’. In the screenshot below, the highlighted field ‘Current Revision should show a value of ‘2’ as that is the only active revision.

Use a summary saved search of that revision record. Set that search as the source of your header custom field.

Thanks for your reply, I have tried this solution in the past and it worked fine. However, this time around, the saved search needs to be setup on the custom record and the created custom record is not showing up in the field dropdown list in the saved search results tab. Maybe I am missing some option, the search is also set to run unrestricted but no luck yet.