In comparing the ep_eh_unique_vs_20130401.xlsx and ep_eh_unique_vs_20130614.xlsx downloadable files from VSAC for April 1, 2013 and June 14, 2013, I found 246 Value Sets that have the Same OID and Value Set Version in the two files, but there are different codes within those value sets between the two files. I would expect the value set version Id/definition Id or expansion Id to change if there are changes to codes within the value set.
For example, the April and June files contain the Value Set "Anticoagulant Therapy" with OID 2.16.840.1.113883.3.117.1.7.1.200. The Value Set has the same Version ID, Definition Id, and Expansion ID (20130401) in both files. However, in April’s file, there are 11 distinct RXNORM codes that did not appear in the June file. If 11 distinct codes were removed from this Value Set between April and June, why are the definition and expansion Ids in June's file the same as the version Id in April's file? (see also JIRA # regarding definition Ids and Expansion Ids).
It appears that 209 of those 246 value sets simply had duplicate codes removed (same code from different versions of the same code set), however 37 value set had distinct codes added or removed