Syntax: "--mca <key> <value>", where "key" is the parameter name and
"value" is the parameter value.

Pass generic MCA parameters — i.e., parameters whose project
affiliation must be determined by PRRTE based on matching the name of
the parameter with defined values from various projects that PRRTE
knows about.

Deprecated: This translation can be incomplete (e.g., if a project
adds or changes parameters) — thus, it is strongly recommended that
users use project-specific parameters such as "--prtemca" or "--
pmixmca".
