Sempahore is a flag-based form of communication, used to visually communicate information over long distances.
Lower case lettes (NO CAPS LOCK REQUIRED) & the following special characters are used:
Period (.) = "Rest" in semaphore.
Pound Sign (#) = "Numbers". Since some letter symbols are also used as numbers, type in # before typing in numbers. Conversely, type "J" to indicate you're going back to letters.
Exclamation Point (!) = "Attention". Type !, when the message is important.
"X" = "Cancel". To nullify the previous message.