Fonts used in the guide

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 $\cal OYST\!ER\,$ software or IDL are denoted in this style: Averaging complete.