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1/23/2015  UT Dallas

POEC 6382 Applied GIS Software

5

Understanding Item Definitions

An item (column) is described in terms of four variables:

name - the name of the item, up to 16 characters in length

e.g. cover-id, landuse, pop97, etc.

type - the data types used to store values

I - integer (one byte per digit)

B - binary integer (requires less storage than I types)

C - character

N - floating point (e.g. decimal) number stored as one byte per digit

F - floating point binary number

D - date (e.g. yyyymmdd)

width - the width of the item in bytes required for storage

I - 1-16 bytes      B - either 2 or 4 bytes

C - 1 to 320 characters      N - 1 to 16 digits

F - 4 for single, 8 for double precision     D - always 8 bytes

For F or N also provide the number of decimal places for real numbers

Output width - the width of item values when displayed

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