Basically, I want to have validation rules run when a step in an approval process is approved. I would like the rule to take into account which step triggered the rule, so that each step can have different requirements for approval. Is this possible? Thanks!
A custom field for Step Number, or the Status field you were referring to
So on each Approval Step, say Step 1 Have an Approval Action to update the field to Step 1, indicating that Step 1 is approved. Have a validation rule which summarises the data requirements for approval
This will return an error to the Approver in each step if they haven't supplied the required information before approving. (The validation rule will be triggered by the Process attempting a Field Update on Approval)
Don't know if an addError via a trigger will be any different.