Reference

Terminal operations glossary

The terms that appear across these guides, defined plainly. Where a definition matters operationally rather than just linguistically, the entry says why.

Measurement and gauging

Net Standard Volume NSV
The volume of product corrected to a standard reference temperature, typically 15°C, and excluding free water and sediment. NSV is what commercial settlement is based on, because it is comparable between tanks and between days regardless of ambient temperature.
Gross Standard Volume GSV
Total liquid volume corrected to standard temperature, including free water and sediment. GSV minus free water and sediment gives NSV. Confusing the two is a common source of reconciliation discrepancies that look like measurement errors.
Ullage
The empty space between the product surface and the tank's top reference point: the inverse of level. Ullage is the operationally relevant figure when planning a receipt, because it answers how much more the tank can take.
Automatic Tank Gauging ATG
Instrumentation continuously measuring level, temperature and often density, replacing manual dipping. Servo, radar and hydrostatic are the common gauge types. ATG output is the raw input from which GSV and NSV are derived, which is why traceability back to it matters.
Throughput
Volume moving through a terminal over a period, as distinct from storage capacity. Most terminal revenue is a function of throughput, and throughput is constrained by asset availability as much as by tank volume.

Systems and integration

CMMS Maintenance system
Computerised Maintenance Management System. The system of record for work orders, preventive schedules, asset registers and completion history. It answers maintenance questions well and holds no commercial or tank context, which is exactly why crossing questions cannot be answered from it alone. How to connect one →
Terminal Automation System TAS
The system controlling and recording product movements: loading gantries, meters, batch control, access. A TAS knows what moved and when. It does not know the condition of the asset that moved it, or which contract that movement served.
OPC Unified Architecture OPC UA
A vendor-neutral industrial communication standard for reading automation and instrumentation data. In a terminal, an OPC UA endpoint is often the cleanest route to continuous gauging data without a proprietary vendor interface.
Modbus
A long-established industrial protocol still widely used by older gauging and automation equipment. Reading it needs a register map rather than vendor cooperation, which often makes legacy kit easier to connect than newer closed systems.
Store and forward
An agent queues readings locally when its link fails and transmits them on recovery. The effect is that an outage produces delayed data rather than a permanent gap, and gaps are the failures that surface later, during an audit.
Outbound-only architecture
An agent inside the plant network initiates all traffic outward; the external platform holds no route in. No inbound firewall rule is opened. This is usually the property that decides whether an OT security review concludes.

Evidence and compliance

HSSE
Health, Safety, Security and Environment: incidents, near-misses, deviations and their corrective actions. Under NIS2, near-miss records carry more weight than they used to, because a significant incident includes one capable of causing severe disruption, not only one that did.
NIS2 Directive EU 2022/2555
EU legislation on cybersecurity risk management and incident reporting. Annex I lists oil transmission and storage operators as essential entities, bringing most bulk-liquid terminals into scope for Article 21's ten measures and Article 23's 24-hour, 72-hour and one-month deadlines. Full guide →
Essential entity
The higher NIS2 tier, subject to proactive supervision: inspections and evidence requests can occur without an incident having happened. Oil storage operators above the size threshold generally land here rather than in the reactively supervised important-entity tier.
Audit trail
An append-only record of state changes, each attributable to an actor and a timestamp, which cannot be silently edited afterwards. The append-only property is what separates an audit trail from a change log, and what makes it usable as evidence. What auditors ask for →
Reconciliation
Comparing what a commercial or movement system reports against what tank measurements imply actually happened. The discrepancy is the useful output. A system that silently picks one source over the other has destroyed the reason for doing it.

Commercial

Revenue at risk
Contracted revenue exposed to a foreseeable event: an expiry inside its notice window, a counterparty concentration, or a commitment against an asset carrying deferred work. It is only calculable when contract terms and asset condition sit in the same record, which is why most operators cannot produce the figure on request.
Deferred maintenance
Identified work postponed rather than cancelled. Its real cost is rarely visible in the maintenance system, because the consequence is throughput or availability on an asset the maintenance system does not know is contractually committed.

Missing a term?

If something in these guides is unclear or a definition here is wrong, say so: corrections are welcome and get made.

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