This is a ready-to-use tag register for a process historian. It is the control that draws the GxP boundary: you cannot validate, review, or defend historian data when you cannot say which tags matter. Replace every <<FILL: ...>> placeholder, keep one row per tag, and maintain it under document control and change control. A worked filled specimen follows. This register is maintained under the SOP: Process Historian Data Integrity Governance. Verify each cited regulation against the current source before you rely on it.
Register header
| Field | Entry |
|---|---|
| Register number | <<FILL: REG-ID>> |
| Historian / system | <<FILL: system name, version>> |
| System owner | <<FILL: name / role>> |
| Last review date / by | <<FILL>> |
| Change control for current state | <<FILL: CC reference>> |
Field definitions
| Field | Format | Required | Maintained by |
|---|---|---|---|
| Tag name | Unique identifier (e.g. BR101.TEMP.PV) | Yes | Automation |
| Description | Human-readable meaning | Yes | Automation / SME |
| Source device | PLC / DCS / SCADA feeding the tag | Yes | Automation |
| Engineering units | degC, bar, L/min, pH, % | Yes | SME |
| GxP classification | GxP-critical / GxP-supporting / non-GxP | Yes | SME + QA approval |
| Classification rationale | Why (CPP/CQA, decision use, or none) | Yes | SME |
| Data criticality | Tied to product/patient impact | Yes | SME + QA |
| Compression setting | Deadband value or “none” | Yes | Automation |
| Compression justification | Numeric basis vs control limits (critical tags) | If compressed | SME |
| Scan / sample rate | Polling interval | Yes | Automation |
| Retention (active + archive) | Duration and basis | Yes | QA |
| Audit trail scope | Config + data / config only / etc. | Yes | Automation / QA |
| Owner | Accountable process/system owner | Yes | System owner |
| Change reference | CC record for current configuration | Yes | Automation |
The register
| Tag name | Description | Source | Units | GxP class | Rationale | Compression | Scan | Retention | Owner | CC ref |
|---|---|---|---|---|---|---|---|---|---|---|
<<FILL>> | <<FILL>> | <<FILL>> | <<FILL>> | <<FILL>> | <<FILL>> | <<FILL>> | <<FILL>> | <<FILL>> | <<FILL>> | <<FILL>> |
<<FILL>> | <<FILL>> | <<FILL>> | <<FILL>> | <<FILL>> | <<FILL>> | <<FILL>> | <<FILL>> | <<FILL>> | <<FILL>> | <<FILL>> |
Add one row per tag. For a historian with tens of thousands of tags, maintain the register in a validated, version-controlled system and treat this table as the field specification for it.
Acceptance criteria
- Every tag in the historian appears in the register with a GxP classification and a rationale.
- Every “non-GxP” classification has a written reason it carries no product or compliance use.
- GxP-critical tags carry no data-hiding compression, or carry a numerically justified deadband.
- The GxP-critical list is QA-approved and any change to a tag’s configuration is under change control with a reference in the register.
- Retention per tag meets the longest applicable requirement.
References
21 CFR 211.68, 211.180-211.188. 21 CFR Part 11. EU GMP Annex 11 (computerised systems) and Chapter 4 (documentation, retention). Note the pending draft Annex 11 revision (consultation closed 7 October 2025, draft as of mid-2026); confirm final clause numbers before citing. MHRA GxP Data Integrity Guidance (2018); PIC/S PI 041 (2021); GAMP 5 (2nd ed., 2022).
Confirm each reference against the current source before issue.
Filled specimen
Illustrative extract for a bioreactor and its utilities. The GxP boundary and the proportionate controls are visible at a glance.
| Tag name | Description | Source | Units | GxP class | Rationale | Compression | Scan | Retention | Owner | CC ref |
|---|---|---|---|---|---|---|---|---|---|---|
| BR101.TEMP.PV | Bioreactor 101 temperature | DCS-A | degC | GxP-critical | CPP in batch record | None (store all) | 1 s | 10 yr | MSAT, J. Lin | CC-2026-0198 |
| BR101.DO.PV | Bioreactor 101 dissolved O2 | DCS-A | % | GxP-critical | CPP in batch record | 0.1% deadband (justified vs 30% control band) | 1 s | 10 yr | MSAT, J. Lin | CC-2026-0198 |
| BR101.AGIT.SP | Agitation setpoint | DCS-A | rpm | GxP-supporting | Supports deviation review | None | 1 s | 10 yr | MSAT, J. Lin | CC-2026-0198 |
| CHW.SUPPLY.TEMP | Chilled water supply temp | SCADA-U | degC | non-GxP | Utility, no product/compliance use | 0.5 degC deadband | 30 s | 1 yr | Facilities, R. Osei | CC-2026-0203 |
| P204.VIB | Pump 204 vibration | SCADA-U | mm/s | non-GxP | Maintenance only, no GxP use | 1.0 deadband | 60 s | 90 d | Facilities, R. Osei | CC-2026-0203 |
The two GxP-critical tags carry no or numerically justified compression, so no excursion of concern is lost, and are retained ten years. The utility and maintenance tags are compressed harder and retained briefly. An inspector can read the boundary and see the controls are proportionate, which is the whole point of the register.
How to adapt this register
- Pull the full tag export from your historian first; the tag count usually surprises people, and you cannot govern what you have not listed.
- Run every tag through the classification test with the SME, then get QA to approve the GxP-critical list.
- For each GxP-critical compressed tag, record the numeric deadband justification against the parameter’s control limits.
- Maintain the live register in a validated version-controlled system; keep this table as its field specification.