The following is a list of location codes that are returned by pipZip4FindFirst and pipZip4FindNext. The location codes indicate how the location and Census ID were defined. In general, the further you are in the alphabet, the less accurate the location.
ZIP+4 centroid location code description—4th character.
| Code | Description |
|---|---|
| A | Created via address matching to a single segment. Location is assigned in the middle of the matched street segment, offset to the proper side of the street. |
| a | Created via address matching to a single segment, but the correct side of the street is unknown. Location is assigned in the middle of the matched street segment, offset to the left side of the street, as address ranges increase. |
| B | Created via address matching to multiple segments, all segments have the same Block Group. Location is assigned to the middle of the matched street segment with the most house number ranges within this ZIP+4. Location is offset to the proper side of the street. |
| b | Same as methodology B except the correct side of the street is unknown. Location is assigned in the middle of the matched street segment, offset to the left side of the street, as address ranges increase. |
| C | Created via address matching to multiple segments, all segments have the same Census Tract. The Block Group that represents the most households in this ZIP+4 is returned. Location is assigned to the middle of the matched street segment with the most house number ranges within this ZIP+4. Location is offset to the proper side of the street. |
| c | Same as methodology C except the correct side of the street is unknown. Location is assigned in the middle of the matched street segment, offset to the left side of the street, as address ranges increase. |
| D | Created via address matching to multiple segments, all segments have the same County. The Block Group that represents the most households in this ZIP+4 is returned. Location is assigned to the middle of the matched street segment with the most house number ranges within this ZIP+4. Location is offset to the proper side of the street. |
| d | Same as methodology D except the correct side of the street is unknown. Location is assigned in the middle of the matched street segment, offset to the left side of the street, as address ranges increase. |
| E | Created via street name matching (no house ranges available). All matched segments have the same Block Group. Location placed on the segment that is closest to the center of matched segments. In almost all cases, this is on the mid-point of the entire street. |
| F | Created via street name matching (no house ranges available). All matched segments have the same Census Tract. Location placed on the segment that is closest to the center of matched segments. In almost all cases, this is on the mid-point of the entire street. |
| G | Created via street name matching (no house ranges available). All matched segments have the same County. Location placed on the segment that is closest to the center of matched segments. In almost all cases, this is on the mid-point of the entire street. |
| H | Same as methodology G, but some segments were not in the same County. This methodology is used for less than .05 percent of the centroids. |
| I | Created ZIP+2 cluster centroid as defined by methodologies A, a, B, and b. All centroids in this ZIP+2 cluster have the same Block Group. Location is assigned to the ZIP+2 centroid. |
| J | Created ZIP+2 cluster centroid as defined by methodologies A, a, B, b, C, and c. All centroids in this ZIP+2 cluster have the same Census Tract. Location is assigned to the ZIP+2 centroid. |
| K | Created ZIP+2 cluster centroid as defined by methodologies A, a, B, b, C, c, D, and d. Location is assigned to the ZIP+2 centroid. |
| L | Created ZIP+2 cluster centroid as defined by methodology E. All centroids in this ZIP+2 cluster have the same Block Group. Location is assigned to the ZIP+2 centroid. |
| M | Created ZIP+2 cluster centroid as defined by methodology E and F. All centroids in this ZIP+2 cluster have the same Census Tract. Location is assigned to the ZIP+2 centroid. |
| N | Created ZIP+2 cluster centroid as defined by methodology E, F, G, and H. Location is assigned to the ZIP+2 centroid. |
| V | Over 95 percent of addresses in this ZIP Code are in a single Census Tract. Location is assigned to the ZIP Code centroid. |
| W | Over 80 percent of addresses in this ZIP Code are in a single Census Tract. Reasonable Census Tract accuracy. Location is assigned to the ZIP Code centroid. |
| X | Less than 80 percent of addresses in this ZIP Code are in a single Census Tract. Census ID is uncertain. Location is assigned to the ZIP Code centroid. |
| Y | Generally indicates a rural or sparsely populated area. Census code is uncertain. Location is based upon the USGS places file. |
| Z | Generally assigned for P.O. Box or General Delivery addresses. Census code is uncertain. Location is based upon the Post Office location that delivers the mail to that address. |