Question mark (?) in SBC CLI

In general, using the question mark (?) in the SBC CLI outputs a small description of the possible commands at that level, that is fine. However, when working with HMRs, the question mark is a valid character when using regular expressions, according to the CLI guide:

 

? question mark Signifies that the preceding character or group in parentheses is optional; the character or group can appear not at all or one time

 

How does one get a "?" character to be used in a regular expression, when typing the regexp in the CLI? Whenever you type it, you get the CLI help, but not the "?" character