The fieldLen property specifies the number of single-byte characters that can be displayed in a form field. This value does not include the preceding attribute byte.
The value of fieldLen for numeric fields must be large enough to display the largest number that can be held in the field, plus (if appropriate) a decimal point and a sign. The value of fieldLen for a field of type CHAR, DBCHAR, MBCHAR, or UNICODE must be large enough to account for the double-byte characters and any shift-in or shift-out characters.
The default fieldLen is the number of bytes needed to display the largest number possible for the primitive type, including all formatting characters.