MIO_DEFAULTS
The purpose of the MIO_DEFAULTS environment variable is to aid in the readability of the data stored in the MIO_FILES environment variable.
If the user specifies several modules for multiple file_name_list and
module list pairs, then the MIO_FILES environment
variable can become quite long. If the user repeatedly overrides
the hard-coded defaults in the same manner, it is simpler to specify new defaults
for a module by using the MIO_DEFAULTS environment
variable. This environment variable is a comma-separated list of modules with
their new defaults, as in the following example:
MIO_DEFAULTS = trace/events=prob.events , aix/debug