AutoLisp provides a set of functions to access and modify graphic entities and their properties. Additionally, some other functions provide direct access to input devices like keyboard, digitizer, and output devices like screen. These functions are specific to AutoLisp and are not part of the standard LISP programming language.
Drawing entities created as part of any AutoCad drawing are stored internally in a database of information. Whenever you perform any operation- addition of a new entity, modification of an entity, or deletion of an entity, the drawing database is updated with new information. To access this database, AutoLisp provides two special data types, called entity names and selection sets.
;get definition data for line
AutoCad provides a set of standard and customizable interaction techniques, using which users can execute various commands. A subset of these techniques involves using menus of various kinds- screen, pull down, icon, button, and tablet menus. Commands to implement these techniques are placed in the acad.mnu file.
A menu file is a plain text file containing command strings. All menu files must have extension .mnu (compiled version will have extension .mnx). Each menu item may consist of a command, a parameter, or a sequence of commands and parameters. By convention, each menu item resides on a separate line in the menu file.
Example: Following is a simple command menu file.
When you select any of these options, AutoCad will execute corresponding command.
Section labels in a menu file assign various options/commands to different devices. In the following example,
labels preceded by *** specify sections of command menu to different devices; in this case, first section to screen menu, and the next one to pop up menu 1. Also note that commands may be given descriptive titles enclosed in  followed by actual commands to be executed when that option is selected.
Menu items can be broken down into logical units and organized to form a hierarchy of main and submenus. Submenus are identified in a menu file by a label of the form **name where name is a valid character string. Submenus can be activated or deactivated using the following construct:
Following menu file is available in: /homes2/prog/ausgabe/09_demo.mnu
Modify the program you wrote for bung 7 so that your program now supports following menus and options.
Menu G_Design with following menu options:
Menu M_Design with following menu options:
A template menu file is provided: /homes2/prog/ausgabe/09_name.mnu. Copy this file into your directory and add appropriate commands and functions to it. You are required to submit your program (09_name.lsp) and menu files (09_name.mnu).