Carl, I'm sorry to hear that your search experience has been so frustrating! I'm just curious what keywords you used when you searched.
I did a quick test using "compatibility matrix creo," and the first two hits included the information I think you were looking for:
For your reference as the compatibility matrix is a reference document you can find it under the Windchill Reference Documents page (located on the main Windchill TS Support Page (http://www.ptc.com/support) under the Product Documentation Section:
As per CS99145, the matrix will pop up if you select the appropriate product (i.e. Windchill PDMLink) as the Product and Document Type "Matrices - Software".