Checks if the duration of the unit is an estimate.
!(p)
All time units _in this class are considered to be accurate, while all date
units _in this class are considered to be estimated.
!(p)
This definition ignores leap seconds, but considers that Days vary due to
daylight saving time and months have different lengths.
@return true if the duration is estimated, false if accurate
Checks if the duration of the unit is an estimate. !(p) All time units _in this class are considered to be accurate, while all date units _in this class are considered to be estimated. !(p) This definition ignores leap seconds, but considers that Days vary due to daylight saving time and months have different lengths.
@return true if the duration is estimated, false if accurate