# Abbreviations We Understand

The industry shorthand that search, equipment tags, and the document reads all share, including the terms that mean more than one thing.

You write "VFD". The engineer writes "variable frequency drive". The panel
schedule says "VFD-101". Submittal Kit treats all three as the same thing, so
you can type whichever one you were looking at.

## Where it shows up

**Search.** Type an abbreviation and you also reach the documents that spell it
out, and the other way round. Your own words come first. If anything in your
workspace says what you typed, that is what you get, and the industry reading
never runs. It only comes out when your words found nothing at all, so it can
rescue a search that failed and cannot muddy one that worked.

**Equipment tags.** VFD-101 reads back as Variable Frequency Drive on the
equipment record, and on hover in the register lists. So you can read a
register somebody else built without asking them. A tag we don't recognize
stays exactly as you typed it.

**Reading your documents.** Scope matching and requirement reading get the
terms your project's text actually uses, handed over with the text itself. So
they read "LCP" as a local control panel instead of inferring it.

## Terms that mean two things

Some shorthand is genuinely ambiguous. "LS" is a level switch on an instrument
list and a lift station on a site plan. "PID" is a control loop to a programmer
and a drawing to a designer. "BOD" is basis of design in a spec and biochemical
oxygen demand in a process narrative.

We do not pick for you. Search looks for both, a decoded tag shows both, and
the document reads get both with a note that the surrounding text decides.
Guessing would be worse.

## Your words still win

This is the vocabulary every integrator shares, so a brand new workspace
understands "RIO" before anyone has typed anything in. Your own naming sits on
top of it. The category, tag and manufacturer aliases you keep in
[Library Vocabulary](/help/library-vocabulary) are yours to edit, and where the
two disagree, yours wins.

Missing a term your projects lean on? Tell us and we will add it. We maintain
this list rather than letting each workspace edit it, which is what keeps it
consistent for everybody.

## The full list

"Tag prefix" marks a term we will decode at the front of an equipment tag.
Commercial terms are deliberately left alone. A register entry tagged "PO-4"
is your numbering, not a purchase order.

### Controllers, panels, and drives

| Term | Reads as | Tag prefix |
| --- | --- | --- |
| PLC | Programmable Logic Controller | yes |
| PAC | Programmable Automation Controller | yes |
| DCS | Distributed Control System |  |
| RTU | Remote Terminal Unit *or* Remote Telemetry Unit | yes |
| HMI | Human Machine Interface | yes |
| OIT | Operator Interface Terminal | yes |
| MCP | Main Control Panel | yes |
| LCP | Local Control Panel | yes |
| VCP | Vendor Control Panel | yes |
| RIO | Remote Input Output | yes |
| VFD | Variable Frequency Drive | yes |
| VSD | Variable Speed Drive | yes |
| RVSS | Reduced Voltage Soft Starter | yes |
| MCC | Motor Control Center | yes |
| ATS | Automatic Transfer Switch | yes |
| UPS | Uninterruptible Power Supply | yes |
| SPD | Surge Protective Device | yes |
| TVSS | Transient Voltage Surge Suppressor | yes |
| CPT | Control Power Transformer | yes |
| PDP | Power Distribution Panel | yes |

### Signals

| Term | Reads as | Tag prefix |
| --- | --- | --- |
| AI | Analog Input |  |
| AO | Analog Output |  |
| DI | Discrete Input *or* Digital Input |  |
| DO | Discrete Output *or* Digital Output *or* Dissolved Oxygen |  |
| IO | Input Output |  |
| PID | Proportional Integral Derivative *or* Process and Instrumentation Diagram |  |

### Instruments and valves

| Term | Reads as | Tag prefix |
| --- | --- | --- |
| FE | Flow Element | yes |
| FT | Flow Transmitter | yes |
| FIT | Flow Indicating Transmitter | yes |
| FM | Flow Meter *or* Force Main | yes |
| LE | Level Element | yes |
| LT | Level Transmitter | yes |
| LIT | Level Indicating Transmitter | yes |
| LS | Level Switch *or* Lift Station | yes |
| LSH | Level Switch High | yes |
| LSL | Level Switch Low | yes |
| PT | Pressure Transmitter *or* Potential Transformer | yes |
| PIT | Pressure Indicating Transmitter | yes |
| PSH | Pressure Switch High | yes |
| PSL | Pressure Switch Low | yes |
| TE | Temperature Element | yes |
| TT | Temperature Transmitter | yes |
| RTD | Resistance Temperature Detector | yes |
| AIT | Analytical Indicating Transmitter | yes |
| ZS | Position Switch | yes |
| ZSC | Position Switch Closed | yes |
| ZSO | Position Switch Open | yes |
| HS | Hand Switch | yes |
| SV | Solenoid Valve | yes |
| CV | Control Valve *or* Check Valve | yes |
| FCV | Flow Control Valve | yes |
| PCV | Pressure Control Valve | yes |
| MOV | Motor Operated Valve | yes |
| ORP | Oxidation Reduction Potential |  |
| TSS | Total Suspended Solids |  |
| NTU | Nephelometric Turbidity Unit |  |

### Networks and protocols

| Term | Reads as | Tag prefix |
| --- | --- | --- |
| SCADA | Supervisory Control and Data Acquisition |  |
| OPC | Open Platform Communications |  |
| MQTT | Message Queuing Telemetry Transport |  |
| DNP3 | Distributed Network Protocol |  |
| HART | Highway Addressable Remote Transducer |  |
| FCP | Fiber Conversion Panel | yes |
| FO | Fiber Optic |  |
| UTP | Unshielded Twisted Pair |  |
| VLAN | Virtual Local Area Network |  |
| POE | Power over Ethernet |  |
| SFP | Small Form factor Pluggable |  |
| NIC | Network Interface Card |  |
| WAP | Wireless Access Point | yes |
| MDF | Main Distribution Frame | yes |
| IDF | Intermediate Distribution Frame | yes |

### Power and code

| Term | Reads as | Tag prefix |
| --- | --- | --- |
| AWG | American Wire Gauge |  |
| NEC | National Electrical Code |  |
| NEMA | National Electrical Manufacturers Association |  |
| UL | Underwriters Laboratories |  |
| AIC | Amperes Interrupting Capacity |  |
| SCCR | Short Circuit Current Rating |  |
| FLA | Full Load Amps |  |
| LRA | Locked Rotor Amps |  |
| HP | Horsepower |  |
| KVA | Kilovolt Ampere |  |
| VAC | Volts Alternating Current |  |
| VDC | Volts Direct Current |  |
| CT | Current Transformer | yes |
| EGC | Equipment Grounding Conductor |  |
| GFCI | Ground Fault Circuit Interrupter |  |
| AFF | Above Finished Floor |  |

### Process

| Term | Reads as | Tag prefix |
| --- | --- | --- |
| WTP | Water Treatment Plant |  |
| WWTP | Wastewater Treatment Plant |  |
| WRF | Water Reclamation Facility |  |
| PS | Pump Station | yes |
| HSP | High Service Pump | yes |
| RAS | Return Activated Sludge |  |
| WAS | Waste Activated Sludge |  |
| MBR | Membrane Bioreactor |  |
| SBR | Sequencing Batch Reactor |  |
| BFP | Belt Filter Press *or* Backflow Preventer |  |
| BOD | Basis of Design *or* Biochemical Oxygen Demand |  |

### Project and commercial

| Term | Reads as | Tag prefix |
| --- | --- | --- |
| RFI | Request for Information |  |
| PCO | Potential Change Order |  |
| SOV | Schedule of Values |  |
| BOM | Bill of Materials |  |
| NTP | Notice to Proceed |  |
| FAT | Factory Acceptance Test |  |
| SAT | Site Acceptance Test |  |
| IFC | Issued for Construction |  |
| IFB | Issued for Bid |  |
| RFQ | Request for Quote |  |
| PO | Purchase Order |  |
| SDS | Safety Data Sheet |  |
| CSI | Construction Specifications Institute |  |
| ISA | International Society of Automation |  |
| GC | General Contractor |  |
| EOR | Engineer of Record |  |
| POC | Point of Connection |  |
| OFCI | Owner Furnished Contractor Installed |  |
| CFCI | Contractor Furnished Contractor Installed |  |

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Submittal Kit · Getting started · Updated 2026-08-19
Canonical: https://submittalkit.com/help/abbreviations