The program differentiated between data for the spreadsheet and a command for the menu by detecting the presence of a backslash character (\). If a user typed a slash, the keystrokes that followed were interpreted as menu commands rather than data.

• 程序通过检查是否有斜线符号（\\）来区分电子表格数据和菜单命令，如果用户输入一个斜线符号，其后的击键将看做菜单命令，而不是数据。