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1 Overview of Fortran 90     continued...

Obsolescent Features
Fortran 90 includes a first step toward a model for planned language evolution as opposed to unbalanced growth or ad hoc removal of features. As with most first steps, this one is small, tentative, and with an as-yet unsure outcome. The idea is to ultimately remove those features that become obsolete as the language evolves, but to officially identify such candidates as ``obsolescent" (in the process of becoming obsolete) well in advance of actual removal. This is intended to give the Fortran community (a) a chance to review the recommendations and prevent mistakes from being made and (b) time to prepare for the change in an orderly way. According to the current model, a feature listed as obsolescent in one version of the Fortran standard is a candidate for removal from the next version.

The following ten features of Fortran 90 are listed as obsolescent:

1.
the arithmetic IF
2.
real (and double precision) DO index variables and expressions
3.
shared DO termination (i.e., two loops terminating on the same statement)
4.
DO loop termination on other than END DO or CONTINUE
5.
branching to an END IF statement from outside that IF construct
6.
alternate return (use a return code variable instead)
7.
the PAUSE statement ( use READ instead)
8.
ASSIGN and assigned GOTO statements (use internal procedures instead)
9.
assigned FORMAT specifiers (use character strings instead)
10.
the H edit descriptor