High Quality Content by WIKIPEDIA articles! In Morse code, prosigns or procedural signals are dot/dash sequences that have a special meaning in a transmission: they are a form of control character. They are normally written as if they were composed of one, two or three ordinary alphabetic characters but they are sent "run together", omitting the normal inter-character spaces that would occur if they were being sent as normal text. These ligatures are properly represented in print by a ligating bar or overline above the letters, indicating that they are linked and sent as one contiguous character.