Header from: http://www.ncdc.noaa.gov/oa/pod-guide/ncdc/docs/klm/html/c8/sec83132-2.htm
Line from: http://www.ncdc.noaa.gov/oa/pod-guide/ncdc/docs/klm/html/c8/sec83143-2.htm
Post-processing:
- cut out all that is not the table and turn HTML-tags into lowercase.
- add codes that can be used for Matlab™ structure fields from avh1b.h in
  the AAPP source distribution.
- use define_avhrr.py to convert to MAT-file struct array
- convert struct array to one structure with fields in 'Id' and values as
  structs
- store this in gac_version4.mat

Note: gac_version4.mat is just added for convenience, as it's easier to
read than the HTML. The reference is in the HTML.