rivt commands are used to read and write external files and assign values to
variables. They typically start in the first column with double vertical bars
followed by the command name, the relative file path and parameters.There are
two exceptions to this pattern - the assignment (=) and definition (:=)
commands are used to evaluate equations.
In the syntax description below, parameters are separated by commas and
parameter options are separated by semi-colons. Commands have a function and
output scope.
