MassGIS explains the unique parcel identifier that is part of the standardization, describes the advantages of adding this unique identifier to your CAMA database, who supports doing this, and what you have to do to implement this step in your community.
What is the parcel mapping standard’s unique identifier?
The standard’s unique identifier for a parcel is referred to as the “locational ID” (or “LOC_ID” for short); it is based on the location of a point inside each parcel in the standardized parcel mapping and is unique statewide.
The LOC_ID is not intended to replace existing map or CAMA record identifiers. However, the LOC_ID does enable tighter and easier integration between your CAMA database and the standardized parcel mapping. This integration is accomplished by incorporating the LOC_ID for each parcel directly into the corresponding tax listing(s) in the CAMA database.
Why is the LOC_ID needed in addition to the unique CAMA ID, the parcel ID, or the GIS ID?
- The LOC_ID, a form of “GIS ID”, enables tighter and easier integration between your CAMA records and their corresponding parcels. Trying to link records based on the map parcel ID information in a CAMA database extract is very inefficient since the parcel IDs are typically stored in several fields (i.e. map, block, lot, etc.). When that map ID information is exported in a CAMA extract, it must be merged together to create one unique parcel ID that matches the same information on the map (for example, the map parcel ID must look like 12_02_2A in both the CAMA extract and on the map – you cannot have 12-02-2A on one side and 12_02_2A on the other); setting up this match is time consuming and has to be repeated every time you want to link the CAMA extract to the parcel map.
- You could attach the CAMA ID (Vision “PID”, Patriot “Account #”, CSC “Link ID”, PK-Systems “Key”, etc.) to each parcel. However, the CAMA ID is unique for every CAMA record. So when you have more than one CAMA record associated with a parcel (for example, condominiums), you have to create some sort of work-around so that the mapping software can link all the condos on one parcel to that parcel. In the standardized parcels, this has been taken care of because the CAMA_ID for each condo on a single parcel will have been paired with the same LOC_ID. Note that this problem also exists with map/block/lot information as condo records in a CAMA database will each have a sub-lot number, but the map parcel ID only goes to the level of the lot number.
- The LOC_ID also solves the problem that neither the map parcel ID nor the CAMA ID are unique outside of any given community. Say, for example, a regional planning agency was asked to map neighborhood codes across multiple communities; they would receive a CAMA extract file from each community. Even if every parcel was tagged with the correct map parcel ID or CAMA_ID, the agency would not be able to reliably link the file from any one community to the regional parcel map because the CAMA IDs could match in multiple communities. Thus at a regional or state level, a unique way of identifying a single parcel or CAMA record is necessary.
- Finally, LOC_IDs lower software application costs because consultants don’t have to modify their GIS applications to use some other identifier for linking your CAMA records with the assessor’s parcel map.
Who supports using the LOC_ID?
Because the LOC_ID is an easier way of linking CAMA records with parcel mapping, it is supported by all the main parcel map maintenance and GIS consultants working in Massachusetts (Tighe and Bond, Polaris Consultants, MainStreet GIS, CGIS Mapping, CDM Smith, Cartographic Associates (now CAI Technologies), and Applied Geographics); it is also supported by all of the regional planning agencies that provide parcel map maintenance services; other GIS consultants likely also support use of the LOC_ID.
In September of 2014, the MAAO endorsed as best practice the use of the MassGIS Parcel Standard.
How do I get the LOC_ID added to my CAMA database?
Having the LOC_ID added to your CAMA database is a step typically completed by your CAMA software vendor (some communities have staff with this type of expertise). An assessor initiates this step by contacting MassGIS for a crosswalk file that you will then provide to your CAMA vendor. The file from MassGIS links LOC_IDs with the corresponding CAMA database unique ID (e.g., Patriot “AccountNo”, Vision “PID”, PK-Systems “key”, CSC “Link ID”, etc.). The CAMA provider then uses that file to update the CAMA database, with the LOC_ID typically being put into an existing “GIS ID” field in the database (in the CSC CAMA an obsolete field is being re-purposed).
Once they are in the CAMA database, how do I keep LOC_IDs up-to-date?
LOC_IDs for new or reconfigured lots are created by whoever maintains your standardized mapping. Whomever maintains your maps needs to provide you with new LOC_IDs for new or changed lots. This is probably best done by having them provide a spreadsheet with map/block/lot information in one column and the corresponding LOC_ID in another column. Use this information to update LOC_IDs as shown in the short training video specific to your CAMA system.