1/23/2015 UT Dallas
POEC 6382 Applied GIS Software
How do you know which item types to specify?
If the attribute values contain any non-numeric characters, you must specify type C.
If the values are numeric with a decimal place, you must use N or F. Storing numeric values as F (floating point binary) allows you to store large numbers in a small amount of space (4 bytes).
If the values are numeric with no decimal, store them as I or B. Again, using B (binary) saves storage space.
You can store numeric values as characters but you can’t manipulate characters arithmetically.
How do you know how much space to specify?
Define the item width for types C, I or N to accommodate the longest value to be stored; unnecessarily long widths waste storage space.
Output width should be sufficient to display the longest character string or numeric value. Always include one space for the decimal and one for negative sign.