Group Length (gggg,0000) Standard Data Elements have been retired. See PS 3.5 2007.
All implementations shall be able to parse Group Length elements, and may discard and not insert or re-insert them; if present they shall be consistent with the encoding of the dataset even if the transfer syntax is changed resulting in a change in the actual length of a group of elements. No implementation shall require the presence of Group Length elements.
Notes: 1. Elements in groups 0, 2, 4 and 6 are not Standard Data Elements. Mandatory requirements for Group Length for groups 0 and 2 are specified elsewhere in the standard.
2. It is recommended that Group Length elements be removed during storage or transfer in order to avoid the risk of inconsistencies arising during coercion of data element values and changes in transfer syntax.