Returns the number of objects in the vgroup if successful and FAIL (or -1) otherwise.
Description
Vaddtagref inserts the object identified by the parameters tag and ref into the vgroup identified by the parameter vgroup_id.
If an object to be inserted is a data set, duplication of the tag/reference number pair will be allowed. Otherwise, the tag/reference number pair must be unique among the elements within the vgroup or the routine will return FAIL (or -1).