iraf.net

Doe anyone know what the values MAG_LERR and MAG_UERR in the ellipse output file represent?
They seem rather small, so I thought maybe that they represent the fraction of MAG which the upper and lower limits are.
e.g. MAG = 21.1 MAG_LERR = 0.0108 MAG_UERR = 0.0107, and the upper limit of the magnitude error is MAG_UERR times MAG.

However its also possible that they represent the actual upper and lower limits:
e.g. MAG = 21.1 plus/minus 0.0107 / 0.0108
The ellipse help page only says "lower and upper magnitude errors" which I think is a little unclear.

Thanks!