The Group Length (gggg,0000) Standard Data Element shall be implicitly defined for all Data Element groups with a Value Representation of UL and a Value Multiplicity of 1. It shall be an optional (Type 3 Data Element Type) Data Element in DICOM V3.0 (see Section 7.4 in PS 3.5 for a description of Data Element Types). It provides an optional optimization scheme in partial parsing of Data Sets by allowing the skipping of entire groups of Data Elements. Implementations may or may not choose to encode explicit Group Length in a Data Set. All implementations shall be able to accept or ignore such elements.
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