Signal Type	Identifier
Controlled signals	Signal box abbreviation and signal number on a plate.
Automatic signals	Has '=' on plate above box abbreviation and signal number.
Semi automatic	As above with the word 'semi' in the upper line of the =
Distant signal	Has 'R' or white triangle with the plate showing identifier of the home signal it refers to.
Outer distant	Has 'RR' with the plate showing the identifier of the home signal it refers to.
Banner repeating	Has 'BR' with the plate showing the identifier of the home signal it refers to.
Three state banner repeating	Has 'BR' and a split disk on id plate (shows a white or green proceed banner).
Intermediate home block	Has 'l' on id plate to indicate it splits 2 blocks.
Co-acting signal	Has 'CA' on id plate showing the id of the signal it clones.