OAL – Office of Administrative Law: Responsible for reviewing administrative regulations proposed by over 200 state agencies for compliance with the standards set forth in California 's Administrative Procedure Act, for transmitting these regulations to the Secretary of State and for publishing regulations in the California Code of Regulations.

OAL -- Other Access Line: Facilities used to provide wire line telecommunications service that are neither residential nor business access lines. Example: Coin lines and non-switched access lines.

OCMS – Optional Calling Measured Service: Telephone service that allows residential customers outside the San Francisco and Los Angeles metropolitan areas to call over specified routes within a 40-mile radius at reduced rates.

OCR – Optical Character Recognition: The ability of a light sensitive, optical scanning device to sense characters in hard copy, or printed copy, and to convert them into digital form for electronic processing and transmission.

OCTA – Orange County Transportation Authority: OCTA creates, funds and delivers efficient transportation for Orange County . They oversee extensive bus and paratransit service, Metrolink commuter rail service, the 91 Express Lanes toll road, freeway, street and road improvement projects, motorist services and by regulating taxi operations. 

OEPC – Operating Expense Per Customer: Total operating and maintenance expense divided by total number of customers.

OES – Office of Emergency Services: Coordinates overall state agency response to major disasters in support of local government. The office is responsible for assuring the state's readiness to respond to and recover from natural, manmade, and war-caused emergencies, and for assisting local governments in their emergency preparedness, response and recovery efforts.

Off-peak Gas: Gas that is to be delivered and taken on demand when demand is not at its peak.

Off-peak Service: Service made available on special schedules or contracts on a firm basis but only for a specified time during the portion of the load cycle of lease use.

Offset Rate Increase: A rate increase to pass on to customers the cost of increases that are beyond a utility's control, e.g., to cover increased Ad Valorem Taxes (property taxes collected by a county on the valuation of a utility's assets).

OGA – Office of Governmental Affairs: A Division of the PUC that represents the PUC before the State Legislature and Executive Branch, and oversees representation of the PUC and State of California before the U.S. Congress and federal agencies.

Ohm: The unit of measurement of electrical resistance. The resistance of a circuit in which a potential difference of 1 volt produces a current of 1 am pere.

OII – Order Instituting Investigation: A motion initiated by the PUC to explore broad policy issues, resolve procedural matters, investigate charges of improper or illegal activity by a regulated utility or transportation company, or respond to directives from the Legislature. An OII will name one or more utility companies as respondents and usually require them to take specific action, e.g., file data or comments on a particular subject or respond at hearings to matters covered in the OII.

OIR – Order Instituting Rulemaking: An investigatory proceeding opened by the PUC to consider the creation or revision of rules or guidelines in a matter affecting more than one utility or a broad sector of the industry. Comments and proposals are submitted in written form. Oral arguments or presentations are sometimes allowed. The PUC's decision is often implemented in a General Order (GO).

OIS – Outage Information System: A computer system used by utilities to track and transmit information on system outages and problems.

OMPC – Operating Margin Per Customer: Operating revenue less operating expense divided by total number of customers.

ONA – Open Network Architecture: The concept of network services planning, design, and placement that ultimately makes available to the customer the capabilities possessed by the Independent Telephone Companies.

OP – Ordering Paragraph: The section of a PUC decision that orders the utilities/parties to comply with certain rules/regulations.

Open Access: A regulatory mandate to allow others to use a utility's transmission and distribution facilities to move bulk power from one point to another on a nondiscriminatory basis for a cost-based fee.

Open Season: Designated time period in which potential customers for a proposed transmission or storage project must submit their service elections for capacity to the interstate pipeline, utility, or storage provider. For the PUC-regulated utilities, noncore customers that do not elect firm capacity during an open season may receive default service, or they may continue to receive service based on prior elections depending upon tariff provisions and available capacity.

Operable Nuclear Unit: A nuclear unit is "operable" after it completes low-power testing and is granted authorization to operate at full power. This occurs when it receives its full power amendment to its operating license from the Nuclear Regulatory Commission (NRC).

Operating Ratio: The ratio of operating expenses to pertinent revenues.

Optical Scanner: A device that scans both written text and graphics and converts them into digital information suitable for electronic processing or transmission.

ORA - Office of Ratepayer Advocates: A Division of the PUC that participates in PUC proceedings, workshops, and other forums with significant dollar impacts on consumers, that address issues of consumer protection, development of fair rules for competition or other significant policy issues, and that address service quality, rate levels, and rate of return. ORA's mission, as defined by Senate Bill 960 in 1996 and embodied in Public Utilities Code Section 309.5, is to "obtain the lowest possible rate for service consistent with reliable and safe service levels."

Original Cost: The actual cost of property to the party who first dedicated it to public use as utility property.

ORTS – Optional Residential Telephone Service: A measured rate service available either to specific communities or to all communities within a specified radius of 40 miles which is available to residents of the San Francisco , Los Angeles , and Orange County metropolitan areas.

OSP – Operator Services Provider: Independent companies offering telephone service on a local or toll (long distance) basis, in competition with local telephone companies.

OSS - Operations Support System: The system that performs management, inventory, engineering, planning and repair functions for communication service providers and their networks.

OT – Offered Traffic: The number of call attempts in any specified period of time.

Overdraft: Removal of groundwater by pumps and wells more rapidly than it is naturally replenished; groundwater "mining".

Ozone: A highly reactive form of oxygen used to disinfect water.