Beams are the fat lines connecting notes of equal duration (shorter than quarter notes). The notes connected by a beam belong to the same note cluster. MusiCAD automatically clusters notes according to barlines and time signature.
If there are many (4 or more) sixteenth notes (or shorter) in a cluster, you can further subdivide the clustering to increase readability. For this you use from the note properties menu the button
On the fourth note of the second cluster, the bar is partially broken with <ctrl-'>. Splitting a cluster is done with <'>. Combining notes or clusters together into a larger cluster with <,> (on the last note).
In music with more voices on a staff, it may be necessary to provide the individual parts with their own beams. See double cluster.