The rate in force
Rate schedules, amendments and side letters change what was owed on specific dates. Payment systems rarely hold that history, so approval checks arithmetic instead of entitlement.
Reconstructing the terms in force at each event turns a commercial disagreement into a documentary one.
Rights already held
Most recovery in our engagements is pursued under audit, clawback and representment rights that the client already had and had never exercised, because the trigger depended on a fact no system carried.
PERISCOPE briefings describe investigative principles. They do not disclose detection logic, thresholds, formulas, weighting or rules.