When creating a new CAD document in creo, how can I change Windchill settings where the number does not have .prt appended?

When creating a new CAD document in creo, how can I change Windchill settings so the number field does not auto populate where .prt is not appended?

Per below example: I created a new creo CAD file, file name is 46689090.prt.

But the number field will append the .prt to it, how can I make it come in with the just the 8-digit number?

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