Note durations are represented using real numbers (floats). For example, 4.0 stands for a whole note, 2.0 for a half note, 1.0 for a quarter note, and so on. The music library defines the following constants for common duration values:

WN, WHOLE_NOTE = 4.0
DHN, DOTTED_HALF_NOTE = 3.0
DDHN, DOUBLE_DOTTED_HALF_NOTE = 3.5
HN, HALF_NOTE = 2.0
HNT, HALF_NOTE_TRIPLET = 4.0/3.0
QN, QUARTER_NOTE = 1.0
QNT, QUARTER_NOTE_TRIPLET = 2.0/3.0
DQN, DOTTED_QUARTER_NOTE = 1.5
DDQN, DOUBLE_DOTTED_QUARTER_NOTE = 1.75
EN, EIGHTH_NOTE = 0.5
DEN, DOTTED_EIGHTH_NOTE = 0.75
ENT, EIGHTH_NOTE_TRIPLET = 1.0/3.0
DDEN, DOUBLE_DOTTED_EIGHTH_NOTE = 0.875
SN, SIXTEENTH_NOTE = 0.25
DSN, DOTTED_SIXTEENTH_NOTE = 0.375
SNT, SIXTEENTH_NOTE_TRIPLET = 1.0/6.0
TN, THIRTYSECOND_NOTE = 0.125
TNT, THIRTYSECOND_NOTE_TRIPLET = 1.0/12.0