IV.1 Introduction: Street Codes and Geographic Retrieval Consistency
This chapter discusses street codes, a set of numeric codes assigned in the Geosupport System to the city’s street names and the names of certain non-street geographic features, place names, pseudo-street names and intersection names (see Chapter III.6). (In this chapter, except where otherwise stated, the terms ‘street’ and ‘street name’ refer to any geographic feature or feature name that has a Geosupport street code assigned to it.) Geosupport’s street code feature provides critical support for many types of applications.
The primary purposes of the street code feature are:
• To enable applications to retrieve or match data from their own files by geographic location in a consistent manner: (See Chapter I.3 for a general discussion of the concept of geographic retrieval consistency.) Some streets have more than one name, and some street names have alternative spellings. Therefore, for applications that must retrieve data by types of geographic locations that are defined in terms of streets, such as addresses and intersections, the consistency of the retrieval is an important design consideration. For example, suppose a record is created in an application file for the Manhattan address 1204 SIXTH AVENUE. It is desirable that the application be able later to retrieve this record whether the user specifies the input address at retrieval time as 1204 SIXTH AVENUE, 1204 6 AVENUE or 1204 AVENUE OF THE AMERICAS. To achieve such consistency, Geosupport five-digit street codes rather than street names should be used in the retrieval key, as explained in this chapter.
• To obtain ‘preferred’ street names: For streets that have more than one name, the street name that is most appropriate to use for display purposes (such as on application screens, reports and mailing labels) may vary along the street. Street codes can be used to obtain location-specific ‘preferred’ street names for display, as explained in Chapter IV.6.
Secondary purposes of the street code feature are:
• To improve execution efficiency via street code input : There is an optional feature in which applications can pass input streets to Geosupport in the form of street codes rather than street names. This feature is useful when processing an application file that already contains street codes retained from a previous pass through Geosupport. The use of this feature can increase the execution efficiency of batch applications by sometimes allowing Geosupport to circumvent street name normalization and street code retrieval processing.
• To save application disk storage space: Storing street codes, instead of street names, in an application file saves application disk storage space. In many applications, however, doing so would necessitate increased programming and increased execution time overhead to make additional Geosupport calls to obtain street names for display. Note, however, that with Extended Work Areas, many of the functions return both street codes and street names, thus additional programming is not needed.
The use of Geosupport street codes in an application does complicate the design and development of the application. It also adds a maintenance burden to the application, since street codes stored in an application file must be periodically resynchronized to reflect street code assignment changes effectuated in new Geosupport releases. In view of this overhead, the secondary purposes listed above are not likely by themselves to justify incorporating the use of street codes in an application.