psel <is>,<ip1> [,<ip2>, ...]
This command allows the user to associate certain phases <ip1>
to <ipn> with a given data set <is>. One extreme would be to have
e.g. two data sets and one phase each completely separate which is
not really different from running the refinements separately.
However, by using identical refinement parameters one can constrain
any structural parameters between the phases. An example is given
in the Users Guide. The default is that all structural phases are
associated with all loaded data sets.