A data descriptor must be provided for each data item transferred by a READ or
WRITE statement; the descriptors permitted depend on the data type of the item. The
data descriptors all start with a letter indicating the data type followed by an
unsigned integer denoting the field width, for example: I5 denotes an integer field 5
characters wide, F9.2 denotes a floating-point field 9 character wide with 2 digits
after the decimal point. Full details of all the data descriptors are given in the next
section.
The control descriptors are used for a variety of purposes, such as tabbing to specific columns, producing or skipping records, and controlling the transfer of subsequent numerical data. They are described fully in section 10.9.
Note that only literal constants are permitted within format specifications, not named constants or variables.
