Where a document or action meets criteria to initiate a workflow request for approval for that document (eg a purchase order) or action, by a higher authority, then it should not be possible for the user to take any further process steps until that approval has been granted.  For example, it should not be possible for a user to print off (and potentially send to a supplier) a purchase order where the purchase order is still awaiting approval.

This thread gives detail https://community.dynamics.com/business/f/758/t/249863 .

I've recorded this idea in category 'other' as it probably relates workflows in areas other than just purchasing (for example sales quotes with a value over £5,000 might need approval by the sales manager).