| the 26 upper-case letters | A B C ... X Y Z |
| the 10 digits | 0 1 2 3 4 5 6 7 8 9 |
| and 13 special characters: | |
|
.LT. and .GT. to represent operators like < and >. Some of the special
characters, such as the asterisk and parentheses, are also rather overloaded with
duties.
The blank, or space, character is ignored everywhere in Fortran statements (except within character constants, which are enclosed in a pair of apostrophes). Although you do not need to separate items in Fortran statements with blanks, it is good practice to include a liberal helping of them since they improve legibility and often simplify editing. The only limitation (as explained below) is that statement lines must not extend beyond column 72.
The currency symbol has no fixed graphic representation: it appears on most
systems as the dollar "$", but other forms such as "£" equally valid. This variability
does not matter much because the currency symbol is not actually needed in
Standard Fortran syntax.
Most computers have a character set which includes many other printable characters, for example lower-case letters, square brackets, ampersands and per-cent signs. Any printable characters supported by the machine may be used in comment lines and within character constants.
The Fortran character set does not include any carriage-control characters such as
tab, carriage-return, or form-feed, but formatted WRITE statements can be used to
produce paginated and tabulated output files.
Fortran programs can process as data any characters supported by the local hardware. The Fortran Standard is not based on the use of any particular character code but it requires its character comparison functions to use the collating sequence of the American Standard Code for Information Interchange (ASCII). Further details are given in section 7.6.
