Modifiers are not permitted on the Finding Site in TID 5302 “Post-coordinated Echo Measurement” since such modifiers resulted in different ways of encoding the same concept. TID 5302 requires the use of a single anatomical code that fully pre-coordinates the location details of the measurement. CID 12305 “Basic Echo Anatomic Site” has proven to be sufficient to encode the ASE Core Set of measurements. Implementers are strongly recommended to using codes from that list. If there is a truly significant location detail that needs to be captured, e.g., to identify a specific segment of the atrial wall, or a specific leaf of a valve as the location of the measurement, then the implementer may introduce a new code (CID 12305 is extensible) or better yet, new codes can be added to CID 12305 through a DICOM Change Proposal.