How to get the "User Specified Name" variable?

I have this line of code for getting the part number in the "custom properties" but i want to change it to get the "configuration properties", "user specified name".

i have been searching for quite a while to find it and can't find it in the api help, i have tried to record a macro of me changing the user specified name and i can't get a variable out of it. also i found that if you want the variable to show up in a drawing the link to property variable is called "SW-BOM Part Number (BOM Part Number)"

code

swCustProp.Get2 "PartNo", value, resolvedValOut

SolidworksApi macros