The length of a field on the screen is specified in the format after the field operand, if you give one. If a format is not given, IML uses standard character or numeric formats and informats. Numeric informats allow scientific notation and missing values (represented with periods). The default length for character variables is the size of the variable element. The default size for numeric fields is given with the FW= option (see the discussion of the RESET statement in Chapter 25).
If you specify a named format (such as DATE7.), IML attempts to use it for both the output format and the input informat. If IML cannot find an input informat of that name, it uses the standard informats.