Updates to output file, naming conventions

http://www.cesm.ucar.edu/models/cesm2/naming_conventions.html#modelOutputFilenames
says that

> a new metadata field called time_period_freq is now written to every history file header with one of the corresponding values:
>
> second_N... N ∈ {1..3599} - data are written every N seconds
...
But this is not true for the cpl.hi. files, which seem to contain
instantaneous values.

It would also be helpful to have either a description of the meaning
of the standard characters that follow .h, (a,i,0-9,...) or pointers to that information,
like
http://www.cesm.ucar.edu/models/cesm2/component_settings/cam_nml.html:fincl1
for the first CAM history file.
Similarly, it would be helpful to update the driver namelist documentation
http://www.cesm.ucar.edu/models/cesm2/component_settings/drv_nml.html:history_option
to note that the output will appear in a .hi. file.
Similarly for the cpl.ha* files.

I wouldn't mind writing some of that documentation,
but I can't find the source code for pages like these.
They are not in the CESM2_0 release.
Thanks,
Kevin