In order to facilitate reading this manual, various fonts are
used. Responses you are asked to type in at the command level
appear in these fonts: hds_open,filename. In this
example, a lower-case italic font indicates numeric or character
parameters you have to supply. Procedure names in the text appear
like this: average, whereas widget buttons are typed like
this: OPEN or DISPCORR, depending on whether or not
they bring up a new widget or take immediate action, respectively.
Note, that IDL is not case sensitive Messages from the
software or IDL are denoted in this style: Averaging complete.