From MusiCAD

Duration of music notes is read from the form of the note head or the number of flags (or beams), augmentation dot(s) and/or tuplet notation


Durations of notes and rests can be altered using:

<F5> Shorten cursor-note resulting in a triad-note unless it was already dotted, duration becomes 2/3 of the original duration. Counterpart of <F6>.
<F6> Lengthen cursor-note with half its duration. After punctuation (if meaningful/possible) duration becomes 3/2 of the original duration. Counterpart of <F5>)
<F7> Half duration of cursor-note.
<F8> Double duration of cursor-note. Duration 2/1 will be drawn as brevis duration 3/1 or more as longa .
<alt-5> Shorten to quintuplet duration
<alt-7> Shorten to septuplet duration

Choose default duration for entering notes:.

<1> choose duration 1/1, whole note, semibreve
<2> choose duration 1/2, half note, minim
<4> choose duration 1/4, quarter note, crotchet
<8> choose duration 1/8 eight note, quaver
<6> choose duration 1/16, sixteenth note, semiquaver
<7> choose duration 1/32, thirtysecond note, demisemiquaver
<3> triad-enter; all new notes get 2/3 of default value.
<5> punctuation-enter all new notes get 3/2 of default value.

With auto-duration enabled using auto or <alt-A> clicking on duration button will alter duration of cursor-note.

Effective play duration can differ wildly from notation especially when using articulation modifiers like staccato.

Duration of grace-notes will not taken into account for displaying bar lines and determining clusterization.