Gets and sets the source spatial reference wkid to be used to select the SourceSpatialReference for the
TransformationInfo object (used to populate a table row).
The SourceWkid is optional. The default is 0. The SourceVcsWkid should also be defined if a vertical coordinate system needs to be selected. If the SourceWkid (and the SourceVcsWkid if applicable) is set, then the corresponding SourceSpatialReference with that wkid (and vcsWkid) will be selected for the TransformationInfo object. Note: only one of: o SourceSpatialReference o SourceWkid, and SourceVcsWkid if applicable o SourceWkt, and SourceVcsWkt if applicable need be set. If the SourceSpatialReference is set, Wkids and Wkts are ignored. If the SourceSpatialReference is null, then Wkids are used. If the Wkids are 0 (or less), then the Wkts are used.