from
The Free On-line Dictionary of Computing (8 July 2008)
PL/I
<language> Programming Language One.
An attempt to combine the best features of {Fortran}, {COBOL}
and {ALGOL 60}. Developed by George Radin of {IBM} in 1964.
Originally named NPL and Fortran VI. The result is large but
elegant. PL/I was one of the first languages to have a formal
{semantic} definition, using the {Vienna Definition Language}.
{EPL}, a dialect of PL/I, was used to write almost all of the
{Multics} {operating system}. PL/I is still widely used
internally at {IBM}. The PL/I standard is ANS X3.53-1976.
PL/I has no {reserved words}. Types are fixed, float,
complex, character strings with maximum length, bit strings,
and label variables. {Arrays} have lower bounds and may be
dynamic. It also has summation, multi-level structures,
{structure assignment}, untyped pointers, {side effects} and
{aliasing}. {Control flow} constructs include goto; do-end
groups; do-to-by-while-end loops; external procedures;
internal nested procedures and blocks; {generic procedures}
and {exception handling}. Procedures may be declared
{recursive}. Many implementations support {concurrency}
('call task' and 'wait(event)' are equivalent to {fork}/join)
and compile-time statements.
{LPI} is a PL/I {interpreter}.
["A Structural View of PL/I", D. Beech, Computing Surveys, 2,1
33-64 (1970)].
(1994-10-25)