Commissioning and Pre-Startup.
Commissioning works off the as-installed reality, not the IFC drawings construction worked from. Late field changes, mismatched tag plates, and instruments swapped mid-build all have to reconcile against the master tag list before turnover.
Use it through the lifecycle.
Pre-startup safety review and the IEC 61511 proof-test program both require the instrument index to reflect as-installed reality, not the IFC snapshot. Reconcile the extracted as-built tag list against the live DCS and PLC point tables before the PSSR clock starts.