These text types were designed to represent all forms of song lyrics. However, their use is not limited to lyrics; you can use any lyrics text for any purpose you like, but MusiCAD will just regard it as plain text without any special meaning
Music directions 1 (typically above staff for tempo directions, e.g. adagio)
Music directions 2 (typically below staff for dynamic directions, e.g. crescendo)
Music directions 3 (typically used for score markers)
Note that when you need more lyrics lines and don't use the music directions, you may use music directions for lyrics as well.
Chord symbols are a special kind of text in that they can be transposed automagically along with the notes, and typesetting will be specialized such way that a b will be replaced with A-flat, and some chord related super/sup-scripting will be used as long as chords are assigned a MusiCAD-specific font