List versions of FACTS supported by
You can supply any of these versions to functions engine-specific
functions such as
A character vector of supported FACTS versions.
If your FACTS file does not perfectly agree
with one of the supported versions,
rfacts will try to find
the best version for you, either
The greatest supported version less than or equal to the one in the FACTS file, or
The lowest supported version if (1) does not exist.