"List of Forbidden Phrases" is the list of expressions which, if present, make the message "censored". It is enough only for one of these expressions to be found in the message to label it censored. The filter is not case-sensitive.
For example: by adding the phrase "cs" to the "List of Forbidden Phrases" - the messages "go cs", "go CS?", and also "Tell me, please, what type is it better to use CString or LPTSTR?" - are labeled "cencored":)
It is enough to click on it twice to edit a previously entered phrase.