The "notepad" in question is probably the one you can see while at the Sonar station. You can click on the little red triangle on the notepad and cycle through three different target identifiers; unknown/merchant/warship. I've noticed that if I am manually using the sonar and pickup a sound and I know it's, for example, a merchant I can click on the notepad, cycle to 'merchant' click on the 'x' which will confirm the target as such and then my sonar man will take up the scenario by saying "merchant! Bearing xxx etc".
That doesn't really answer your question but may help in some way.
