A note or annotation can be added and attached to a specific signal and timestamp by right clicking on the signal at the desired time and selecting add note. Type the desired text and press enter to add the note.
There are no limits to the number of notes that can be added to a signal or data bucket.
*note: You can add emojis to the note by copy/pasting the desired emoji. If you are using MacOS, the shortcut key to pull up the emoji selection dialog box is Control + Command + Spacebar.