Adding scale, offset, units metadata to geotiff

[John Caron <caron@xxxxxxxxxxxxxxxx>]

FYI:

Martin Daly and I are discussing adding this tag to the thredds server 
geotiffs:

 http://www.awaresystems.be/imaging/tiff/tifftags/gdal_metadata.html


this would allow us to put out 8-bit geotiffs, but clients could convert 
back to floats, using a scale and offset.
We can specify the units also!!

Any comments on this idea are welcome.