You can use a question mark (?) or question mark and asterisk (?*), in
 key definitions to prompt the user for input.  The ? is replaced by the
 characters read from the terminal before the command is executed.  A
 prompt string enclosed in single quotation marks may follow the ?.  A
 response to an input request generated by a ? must be terminated by
 pressing a keypad or function key, whereas a response to a ?* can be
 terminated by pressing a keypad key, a function key or the return key.