This attribute identifies the rest frame in which the source velocity or redshift is
stored (the source velocity or redshift is accessed using attribute
SourceVel). When
setting a new value for the SourceVel attribute, the source velocity or redshift should
be supplied in the rest frame indicated by this attribute. Likewise, when getting the
value of the SourceVel attribute, the velocity or redshift will be returned in this
rest frame.
If the value of SourceVRF is changed, the value stored for SourceVel will be converted
from the old to the new rest frame.
The values which can be supplied are the same as for the StdOfRest attribute (except
that SourceVRF cannot be set to " Source" ). The default value is " Helio" .