VII.7 Borough Boundary Processing (Functions 2, 3 and 3C)
All of the street configuration functions other than Function 3S allow users to specify locations that lie along a boundary of two boroughs in terms of streets from both boroughs. Function 2, for example, accepts the intersection of Brooklyn’s Ridgewood Avenue and Queens’s Rockaway Boulevard as a valid input street intersection lying on the Brooklyn Queens boundary. A more unusual example that Function 2 also accepts as a valid input intersection is the intersection of Atlantic Avenue in Brooklyn and Atlantic Avenue in Queens. Although physically, Atlantic Avenue is a single continuous street that crosses the Brooklyn-Queens border; Geosupport treats the portions of Atlantic Avenue in the two boroughs as two different streets, and therefore recognizes their meeting point at the borough boundary as an intersection.
A borough boundary location can be specified in terms of streets from different boroughs as follows. For street input data that are in the form of street names, there are three WA1 input fields for borough codes called Borough Code 1, Borough Code 2 and Borough Code 3 (see the WA1 layout in Appendix 2). These fields correspond respectively to the three WA1 input street name fields called Street Name 1, Street Name 2 and Street Name 3. A value is always required in Borough Code 1. If no values are loaded into Borough Code 2 and/or Borough Code 3, the default values are the value in Borough Code 1. When not all of the input street names are in the same borough, the proper value(s) must be inserted into Borough Code 2 and/or Borough Code 3, as appropriate.
If the street input data are in the form of street codes, either as PB5SCs or as B10SCs, each input street code field contains a borough code in its first byte position. This makes it possible to specify input streets from different boroughs using street code input.
The borough boundary processing feature described in this section is not implemented for Function 3S, which requires all three input streets to be from the same borough. If the input streets are in the form of street names, the borough must be specified in the WA1 input field Borough Code 1; Function 3S ignores the contents of the WA1 input fields Borough Code 2 and Borough Code 3.