What is the first step in transmitting a mandatory directive over the radio?

The first step in transmitting a mandatory directive over the radio is for the dispatcher to state their intention to transmit. This initial statement serves several critical functions: it prepares the receiver for the upcoming transmission, ensures that the communication channel is clear, and alerts all parties involved that important information is about to follow. By clearly indicating their intention, the dispatcher helps prevent misunderstandings and ensures that the receiver is attentive and ready to properly receive and acknowledge the directive, which is essential for safety and operational efficiency in railway communication.