VPLX is written in FORTRAN 77, but users are not required to know Fortran. Instead, users specify the application in the VPLX language.
Currently, the VPLX language is undergoing major revision. For example, the following sample of old syntax,
subtract persons minus rooms into test if test (1-high) then _ constant 1 into overcrowded end if
is equivalent to the following new syntax,
if persons > rooms then overcrowded = 1;
As this example illustrates, the new syntax incorporates features of Fortran, the SAS language, and other computationally oriented languages.
VPLX applications are organized into a series of steps. The new syntax has been implemented in the CREATE step and the closely related REWEIGHT step. The current production version of VPLX, 1998.09, incorporates these revisions. Version 1998.09 also runs applications with CREATE or REWEIGHT steps written in the old syntax. Thus, this version is recommended to all users except PC users running Windows 3.1.
A beta version is currently undergoing testing at the Census Bureau. It incorporates revised syntax for the TRANSFORM step. It will also support older applications.
Consequently, all but Windows 3.1 users are currently encouraged to work with the production release.
VPLX has also been compiled under VAX VMS and some other environments, but only PC and UNIX versions are currently maintained on this site.