In the figure above is shown an example of what we mean. Here we have a track-group called all comprising two other track-groups called brass and strings. In turn the brass track-group consists of the two tracks horn and trumpet, while the strings track-group comprises two tracks called violin and cello. In the horn track we show a three note chord and in the violin track a two note chord. The other tracks have a single note. In the Zel realization, the track declaration statement creates the required tracks and track-groups. The text "all" activates the all track-group and notes are then delivered to the correct tracks by using parentheses () to delimit them. You don't have to create chords, tracks or track-groups, all these are optional, but doing so will make your work more structured, more easily understood by those reading your creations and, most important easy to edit. Now we will look at each of these objects in a little more detail.