iXPRESS - What gets created in a Pointfile?

A Pointfile is a database containing geographically referenced data. The pointfile contains a record for each point is inside the selected study area.

When you create a pointfile, you must select the geographic target type to be exported; for example, a pointfile record can represent a block group, census tract, county or state.

Each pointfile record contains the following information:

  • Area Name - For the target (for example county or place name).
  • Code - For linking with other databases or map files. This is usually a standard census area code (FIPS code for USA census areas), or a postal ZIP code.
  • Longitude and Latitude - Coordinates for the target’s centroid. This information lets you use the file directly with many mapping systems.
  • Data Columns - For each variable in a selected category. These are normally numeric, unless the data variable evaluates to text (as is the case for “dominant group” variables).
  • Status Field - This is a character field containing one character for each of the exported variables. The characters are normally all ‘0’s, unless the corresponding variable contains an invalid result (for example an invalid formula, a number too large to be represented, or a division by zero), in which case the character is set to ‘1’.
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