A block bell is provided for each pair of running lines - to 'call attention' of the signalman at the remote end, click with the left-button over the block instrument. Most bell codes are sent after calling attention, but there are exceptions. A menu of the available bell codes is obtained by clicking on the brass plate on the block shelf (or by clicking again over the block instrument) - then select the relevant bell code from the menu. This menu is context-sensitive and will only show appropriate bell codes, only those that are appropriate are available (in black) to be chosen.
If you receive 'call attention' then several things will happen - you will hear the bell (of the correct tone for the box or line to which it applies), you will 'see' it vibrate, the words 'UP LINE' or 'DOWN LINE' on the block instrument will show red and an indication of the bell codes available will be given in the box to the left of the 'Simulation speed' display. Click with SELECT (left-button) on the block instrument to acknowledge call attention and listen to the bell code you will receive. Clicking SELECT on the block instrument again will bring up a menu of the bell codes you might wish to use to reply, clicking ADJUST (right-button)means you wish to ignore the code you received and, instead, send call attention to him.
The signalling regulations are briefly described in a seperate chapter.