If the reference is undefined, translates it into a defined one beginning at zero with a span from zero.
For convenience, an undefined time references reports a frame of zero.
true
for a TimeRef
whose offset
is smaller than its span start, false
for TimeRef.Undefined
.
true
for TimeRef
, false
for TimeRef.Undefined
.
Offsets within the logical span of the object.
The span is of an undefined time reference is void.