Clocking Angles Enquiry

I am using Creo Parametric Release 6.0 and Datecode6.0.6.0

Our engineers have a query regarding creo, see below: We need some help on CREO piping module - clocking angles. At the minute, there is a discrepancy between the CAD and the measured angles on the machine. We want to understand, how CREO measures the angle between to the end coupling oriented in 2 different planes.