[udf-dlm-develop] Preliminary support for UNITS

[Eduardo S. <es...@la...>]

Dear all,

I have just checked in some major edits to udf.c:

  UDF_OPEN() now accepts a UNITS= keyword, which can be a scalar or vector.

  Either way, the number(s) passed to UNITS are *NOT* UDF unit numbers!
  They are _ordinal_ numbers, selecting the Nth (zero-based) unit defined
  for a given sensor.  That is, if we have a PIDF as follows (HENA):

  Group  0: Neutral Hydrogen Pixels
     0 SSD H Elevation 0     0    s0    0,4,7,8
     1 SSD H Elevation 1     1    s0    0,4,7,8
     2 SSD H Elevation 2     2    s0    0,4,7,8

  ...then:

     calling with "UNITS=0" will select unit 0 for all sensors
     calling with "UNITS=1" will select unit 4
     calling with "UNITS=2" will select unit 7
     calling with "UNITS=3" will select unit 8
     calling with "UNITS=99" will select unit 8

     calling with "UNITS=[0,1,2,3]" will select unit 0 for sensor 0, 
     4 for 1, 7 for 2, and 8 for 3.  Although that's silly for this 
     VINST, it might make sense for others, and the capability is 
     there if you need it.

    The default is "999", which just means "the last defined unit".

There's still quite a ways to go.  In particular, I need to fix 
some of the named structure handling, add lots of error checking, 
and update the documentation before it can be released. 

If you have an immediate need for this functionality, "cvs update"
will get you the latest code.

Hope this helps,
^E