… there is a ‘Specification Workshop’ at the SAFe program-level in addition to the ‘Program Backlog Refinement’ program-level event?
This is when an Epic is chunked down into smaller chunks called ‘Features’. These Features must go through Divergent, Emergent, and Convergent thinking based on intent and not on specificity. The Features will then go on for further refinement and prioritization — the Program Backlog Refinement event.
The same specification workshop is actually applied on all levels in SAFe.
Refer to the SAFe Requirements Model — read it and be familiar with it.