Open Watcom FORTRAN 77 Language Reference

3 Names, Data Types and Constants
3.1 Symbolic Names
Symbolic names are names that represent variables, arrays, functions, etc. Names are formed using any of
the upper-case letters A-Z and the digits 0-9, the first of which must be a letter. Symbolic names are
limited to 6 characters in length. The following are examples of symbolic names.
AMOUNT
AGE
CUST73
Open Watcom FORTRAN 77 extends the allowable characters that can make up a symbolic name to
include the lower-case letters a-z, the dollar sign ($) and the underscore (_). Note that the dollar sign and
the underscore are treated as letters and are therefore allowed as the first letter of a symbolic name.
Furthermore, Open Watcom FORTRAN 77 allows symbolic names of up to 32 characters. The following
are examples of permissible symbolic names.
Evaluate
$Cheque
ComputeAverage
_device
IO$ERROR
student_total
Open Watcom FORTRAN 77 makes no distinction between upper and lower case letters. The following
symbolic names are identical.
Account
ACCount
ACCOUNT
Spaces are allowed in symbolic names and are ignored. The following symbolic names are identical.
C R E DIT
CRE D I T
FORTRAN 77 allows certain keywords such as WRITE to be used as symbolic names. In Open Watcom
FORTRAN 77, all keywords satisfy the requirements of a symbolic name. A keyword is a sequence of
letters that is interpreted in a special way by Open Watcom FORTRAN 77. Whether a string of characters
is interpreted as a keyword or as a symbolic name depends on the context in which it is used. In the
following example, the first statement is an assignment statement assigning the value 2 to the symbolic
name DO10I. The second statement is the beginning of a DO-loop.
Symbolic Names 151