The user needs only to say file open, for instance, to access the open file dialog box. Command and control is the simpler of the two speech input modes in terms of programming. It is simpler, in part, because the range of recognizable words is limited. Using the menu example, the word list may be only as long as the number of menu items the user is allowed to speak. Existing applications may be retrofitted for command and control in a few lines of code and perhaps the addition of a word list.
Dictation is the second speech input mode.
In this mode, users may speak freely to the computer, which translates the speech into text. In contrast to command and control, the word list is greatly expanded by definition, to the size of a dictionary. Dictation makes no attempt to recognize the words as commands. Programming for dictation is more complex than for command and control. This applies not only to programming new applications but retrofitting existing ones as well.