I.2 System Functionality

The output information that Geosupport provides consists of geographic information only. Geosupport does not provide, for example, population or crime statistics, housing data, building code violations, property ownership etc. Such data are available from the U.S. Bureau of the Census, city agencies and other sources. Geosupport can facilitate matching many such statistical and administrative databases with user data containing individual locations, by associating those locations with district identifiers needed for such matching, such as census tract, ZIP code or tax block.

Geosupport processes New York City geography only, and is highly customized for that geography. For example, Geosupport can recognize and process many alternative names, spelling variants and partial names of New York City streets; the various address number formats that occur in the city; both old and new addresses on streets that have been renumbered; unique addressing schemes that exist in certain neighborhoods; and many other idiosyncrasies of New York City’s geography

Geosupport is organized into more than a dozen distinct functions that can be accessed by the user. Chapter I.4 contains a brief overview of Geosupport’s suite of functions. The typical function accepts as input geographic locations of a particular type, such as addresses, street intersections or tax lots, and provides some or all of the following services, depending on the function and on calling options chosen:

• Geosupport standardizes and encodes components of the user input data. Specifically, it reformats input street names and input address numbers into standard formats, a process called ‘normalizing’, and it provides numeric street codes corresponding to input street names.

• Geosupport validates the input data. The nature of the validation performed depends on the function requested and the type of call made. Validation of geographic data is a particularly powerful tool in the interactive environment, where it can help applications to trap keying errors and street name misspellings at the point of initial data entry when such errors are most easily rectified.

• Geosupport geocodes the input data. That is, it outputs a predefined set of ‘higher-level’ geographic information associated with the input location, such as the community district, ZIP code, police precinct, cross streets.

• Geosupport enables consistent retrieval of user application data by geographic location. That is, it supports the ability of user applications to search (for inquiry or updating) or match their own data files by geographic location in a way that is independent of possible variations in referring to locations.

The nature of each application determines the combination of these services that is relevant. For example, some applications need only to validate geographic locations, not to obtain any of the output information that Geosupport provides. The fourth type of service, support for geographic retrieval consistency, is relevant only for applications that retrieve or match data from their own files by geographic location (as distinct from Geosupport’s retrieval of data from its internal files). For those applications, geographic retrieval consistency is a critical issue. The next section of this chapter contains a discussion of geographic retrieval consistency in general terms. Later chapters of this document contain detailed discussions of this topic.