Thanks guys for the prompt assistance and advice.
As you say I hadn't classified the process on the process properties tab and as such it didn't appear as one of the available objects for the event process. I had overlooked the part where it clearly states this in the configuration guide link that I posted above.
"○ For the Add a process operation, you can only define a process of type Add Attribute Process.
○ For the Modify a process operation, you can only define a process of type Modify Attribute Process.
○ For the Delete a process operation, you can only define a process of type Delete Attribute Process."
Cheers!
Pat