Because a lot of actions have been coded, it becomes difficult to remember all commands, options and requested parameters. Therefore menus have been designed that group actions related to the same subject, like xy or sbs do, or to the same working environment, like ttr. The text should allow to recognize easily the purpose of the items and the item order follows the logical order in which the work is usually done. An initial menu go is the starting point of BDA menu mode. It offers a possibility to get basic information and perform various tasks without knowing any of the command names.
The main menu usually presents a second one, more typical of the possibilities offered to solve the problem, and a third level menu may appear before the task is really done. In the menu cascade, the completion of an action with a menu brings back to the previous one.
Basic database query is possible with the main menu go and it is possible to obtain information without knowing anything about the database commands, which fills the schedule of conditions. It is however difficult to provide all facilities with menus, because it will lead to asking too many questions and need too much typing. The present menu go is not the best solution for querying data and making subtle selections. The command or prompt modes are better in this case. However, the menu mode offers an easy access to sub-menus that would be called anyway, to use calibrations, to study spectroscopic binaries or work on cross-references. This menu mode is the best way to access them and forget about command names and details of the processes.
Working in the menu mode is described in part II, chapter 8.