How do you edit the Custom Properties List in Summary Information?

I created a new part template that has 12 Property Name fields.  When I check the part into PDM and then check it back out, 6 additional fields have been added to the Property Name fields: Author, Number, Project#, Status, Manufacturer_Part_No. and PartNumber.  I thought that the list of available properties was controlled by the properties.txt file so I found the file (it was not where the File Locations indicated it would be) and modified it.  Now when I select Edit List inside Summary Information, I do only see the properties in the properties.txt file, but what is adding the other 6 fields and how do I edit this?  I now have Part Number, PartNumber and Number.

The image on the left is just prior to check-in to PDM.  The image on the right is after I checked it out from PDM.  There are now 19 Property Name fields.

Thank you for any assistance you can provide.

SolidworksParts And Features