In many cases, the program will offer some guidance, or suggest reasonable default values. You will not go far wrong if you adopt its suggestions. However, experienced observers may have good reasons to ``bend the rules'' a little at times. The program will allow this, though it may complain if you are doing something it thinks is unwise.
In general, input that is comprehensible to an astronomer is also understood by the program. For example, the first and last dates of your observing run can be entered in any reasonable format, so long as the month is specified either in full or by the usual 3-letter abbreviations. Because European and North American conventions for dates differ in the order of month, day, and year, the program will not accept ambiguous forms like 3/8/95. Because of the possibility of misinterpreting dates, the program will tell you how it has interpreted what you typed in, and give you a chance to correct any misunderstanding.
If you make a mistake when entering the name of a file, the program will give you a chance to recover. The program checks to make sure files exist and appear to be of the proper type. The suffix ``.tbl'' will be supplied automatically if you do not type it in. If you mistakenly say there is another star file, and the program finds your last filename does not exist, you can enter ``NONE'' when it asks for another name, and it will go on to the next question.