Insofar as possible, we have tried to follow the FIGARO style of
commands. Thus, capital or lower case letters are identically
treated. A command asks a series of questions, to define the variable
parameters which must be specified for its operation. Each question
is accompanied by a suggested answer. Note that the suggested answer
may change with time depending on what you did previously. If the
suggested answer typed out is ok, hit return, otherwise answer
appropriately and hit return. If you know that the answers to all the
questions following in a given word are the defaults, you can suppress
the rest of the questions by hitting 
followed by return.
There are also ways of putting everything, command and all parameters, onto a single line, which are useful for the simpler commands with few variable parameters. In addition, there are ways of abbreviating the keywords. These points are discussed with many examples in the FIGARO manual, in the section "Introduction for Beginners", which is not repeated here.
Note that in FIGARO and in OBSERVING the name of the frame is the name of the VMS file without the suffix, so that if a file is called A123F.DST, the name of the image for all these commands is A123F. The way the files are named is described in Section V.
If you wish to abort a command before you've gotten to the end of specifying the parameters (i.e., you don't really want to do it or you entered a wrong value for a parameter), CTRL+C (i.e., hit two keys at once) should get you out of it. If that fails, try CTRL+Y. If by doing this you manage to hang up the CCD controller, see the description of the words READY and SECDEL in Section XVII.