Definition of signalled:
(n) :
A sign made to give notice of some occurrence, command, or danger, or to indicate the start of a concerted action.
(n) :
A sequence of states representing an encoded message in a communication channel.
(n) :
Any variation of a quantity or change in an entity over time that conveys information upon detection.
(n) :
(of a radio, TV, telephone, internet, etc.) An electromagnetic action, normally a voltage that is a function of time, that conveys the information of the radio or TV program or of communication with another party.
(n) :
An on-off light, semaphore, or other device used to give an indication to another person.
(v) :
(transitive) To communicate with (a person or system) by a signal.