V.3 Specifying Input Data to the Address-Processing Functions: NAPs, Parsed-Form Addresses, Free-Form Addresses and Unit Information
Functions 1, 1A, 1B, 1E and AP are Geosupport’s address-processing functions. In general, they accept as input conventional street addresses, Addressable Place names, and certain Non-Addressable Place names (NAPs) (described in Chapter III.6 and further discussed in Chapter IV.7). Note, however, that Function AP does not accept Non-Addressable Place names as input.
Addresses can be specified in parsed form, that is, with the house number and street specified in separate WA1 input fields. The street can be specified either as a street name or a street code. Non-street feature names, pseudo-street names and intersection names may not be used. There are two options for specifying an address in parsed form:
- Parsed-form addresses using street name Specify a borough code (or ZIP code), street name and house number (using the WA1 input borough code (or ZIP code) and street name-1 field and either the MSW 12-byte or COW 16-byte WA1 input house number field or the MSW 6-byte WA1 input HNI field or the COW 11-byte HNS field).
- Parsed-form addresses using street code: Specify a borough code (or ZIP code), street code and house number. The borough code and street code may be specified using any of the WA1 input combined borough code and street code fields (the B5SC, PB5SC, B7SC or B10SC) for MSW. For COW, there is only one borough code/street code field. The house number may be specified using either the MSW 12-byte or COW 16-byte WA1 input house number field or the MSW 6-byte WA1 input HNI field or the COW 11-byte HNS field.
Alternatively, addresses can be specified in free-form, that is, with the house number specified together with the street name in the WA1 input Street Name field, as described below. Non-street feature names, pseudo-street names, intersection names and partial street names (see Chapter III.4) may not be used. When addresses are specified in free-form, the input house number and HNI or HNS fields are not used.
NAPs are specified in the same fashion as addresses, as described above, except that typically no house number is supplied. If a house number is supplied with a NAP, Geosupport typically ignores the house number and issues a warning. If the NAP is one that actually has house numbers associated with it, then if the address exists the house number will not be ignored. (See Chapter III.6 for more information.)
Free-form addresses are addresses in which the house number and street name are stored together in a single field, as they might appear in the address line of a mailing address. When an application passes all blanks in the WA1 input house number, HNI and HNS fields, and Geosupport determines that the WA1 input Street Name field does not contain a NAP, Geosupport assumes that the latter contains a free‑form address, and attempts to parse the contents into a house number followed by a street name.
Since both house numbers and street names vary in length, and may be separated by a varying number of blanks, these items will not be in predictable positions within a free-form address. Therefore, when processing a free-form address, Geosupport must parse the contents of the input street name field to attempt to identify and logically separate the house number and the street name. If this is successful, the processing proceeds as with parsed-form address input. If an input free‑form address contains any extraneous data following the house number and street name, such as an apartment number, neighborhood name, borough name or ZIP code, Geosupport attempts to recognize those data as extraneous information, in which case it ignores them, or in the case of COW function calls, Geosupport will also attempt to process the extraneous data as Unit input. (See Chapter V.15 for more discussion of the UNIT feature.)
Geosupport’s processing of free-form addresses is complex and is not as reliable as that for parsed-form address input. It is strongly recommended that, whenever possible, applications be designed to pass input addresses to Geosupport in parsed form, that is, to pass input house numbers and input street names in separate fields.
In order to give users the ability to describe addresses in more detail, Geosupport now allows users to specify UNIT information, e.g. APT 5, on address-processing functions. This feature is described more fully in Chapter V.15.