| NPA | CHAR (3) | Numbering Plan Area code, the first three digits of a 10 digit North American Numbering Plan (NANP) number, commonly called the Area Code. |
| NXX | CHAR (3) | Central Office Code, the first three digits following the Area Code in a 10 digit NANP number, commonly called the telephone exchange or prefix. |
| BLOCK_ID | CHAR (1) | Block identifier. Implies, represents, or identifies either the entire group of 10,000 numbers or a specific group of 1,000 numbers within the NPA NXX. |
| TBP_IND | CHAR (1) | Thousands-block pooling indicator. |
| LATA | CHAR (5) | Local Access and Transport Area (LATA), or LATA-like code of the Rate Center. |
| LTYPE | CHAR (1) | Identifies whether the primary use of the NPA NXX is wireless or landline based on its initial assignment. |
| STATE | CHAR (2) | State or province postal abbreviation of the Rate Center locale. |
| COUNTRY | CHAR (2) | ISO 3166-1 Country Code of the Rate Center locale. |
| RC | VARCHAR (128) | Full name of the geographical Rate Exchange Area, commonly referred to as the Rate Center. A Rate Center identifies the geographic area (i.e. locality, town, or city) served by a particular NPA NXX combination. |
| SWITCH | CHAR (11) | The Common Language® Location Identifier (CLLI) code of the telco switch serving the NPA NXX. This field is generally present for all United States and Canadian records. For NXXs in the Caribbean and Bermuda NPAs, the SWITCH field may be populated with SWCHxxUNKNO, where xx identifies one of the countries or territories in the Caribbean or Bermuda. |
| ZIP | VARCHAR (5) | 5-digit United States ZIP or 3-character Canadian Forward Sortation Area code for the Rate Center locale. |
| ZIP2 | VARCHAR (5) | Second possible ZIP or FSA code |
| ZIP3 | VARCHAR (5) | Third possible ZIP or FSA code |
| ZIP4 | VARCHAR (5) | Fourth possible ZIP or FSA code |
| FIPS | CHAR (5) | United States Federal Information Processing System (FIPS) County Code of the primary county the Rate Center locale is located in. |
| FIPS2 | CHAR (5) | Second possible FIPS code |
| FIPS3 | CHAR (5) | Third possible FIPS code |
| CBSA | CHAR (5) | Core Based Statistical Area Code of the Metropolitan or Micropolitan Statistical Area the Rate Center locale is located in. |
| CBSA2 | CHAR (5) | Second possible CBSA code |
| MSA | CHAR (4) | Historical 4-digit Metropolitan Statistical Area (MSA) code of the MSA the Rate Center is located in. MSA codes have been replaced with the 5-digit CBSA codes. |
| PMSA | CHAR (4) | Historical 4-digit Primary Metropolitan Statistical Area (PMSA) code of the PMSA the Rate Center is located in. PMSA codes have been replaced with the 5-digit CBSA code. |
| LATITUDE | DOUBLE | Latitude in decimal degrees of the general NPA NXX service area. |
| LONGITUDE | DOUBLE | Longitude in decimal degrees of the general NPA NXX service area. |
| OCN_CATEGORY | CHAR (1) | Identifies the general company/carrier "type" of the OCN. |
| OCN | CHAR (4) | 4-character Operating Company Number (OCN) also known as a NECA Company Code, identifying the NPA NXX code-holder or block-holder. |
| DERIVED_FROM_NPA | CHAR (3) | Indicates the previous NPA that existed in the area covered by a given NPA. In cases of overlays, some or all of the previous NPAs may still cover the area. The OVERLAY field should be referenced to determine how to interpret this field. |
| NEWNPA | VARCHAR (20) | Specifies the new area code to be used with the NXX or new area code(s) created in the same coverage area as the current area code. The OVERLAY field should be referenced to determine how to interpret this field. |
| OVERLAY | CHAR (1) | Single character field to determine how the DERIVED_FROM_NPA and NEWNPA fields should be interpreted. |
| LIR | VARCHAR (128) | Name of Local Interconnection Region rate center is assigned to if any. |