| BaseDuration | Base class for date and time durations. | 
| BaseDuration.From |  | 
| DatumDependentDuration | DatumDependentDuration represents durations whose length in milliseconds 
 cannot be determined without knowing the datum point. | 
| Duration | Duration represents time periods which have values independent of the context. | 
| TimeCategory | Apply a number of methods to allow convenient Date/Time manipulation,such as: | 
| TimeDatumDependentDuration | TimeDatumDuration represents a time period which results from an
 arithmetic operation between a TimeDuration object and a DatumDuration object | 
| TimeDuration | TimeDuration represents time periods expressed in units of hours, minutes,
 seconds and milliseconds. |