This Recommendation | International Standard is a work item subdivision of ISO/IEC 15444 that provides extensions of Rec. ITU-T T.800 | ISO/IEC 15444-1 and Rec. ITU-T T.801 | ISO/IEC 15444-2 for logically cuboidal data sets. In particular, it respects all existing capabilities and syntax of Rec. ITU-T T.800 | ISO/IEC 15444-1 and part of the existing capabilities of Rec. ITU-T T.801 | ISO/IEC 15444-2 for multi-component images, while providing alternatives and extensions to some of those capabilities. Within these constraints, it provides an isotropic specification for threedimensional data sets, i.e., the project provides identical processing capabilities in all three dimensions even though Rec. ITU-T T.800 | ISO/IEC 15444-1 and Rec. ITU-T T.801 | ISO/IEC 15444-2 codestream syntax differentiates between the two spatial axes and the cross-component axis. The context models currently used in this Recommendation | International Standard are as in Rec. ITU-T T.800 | ISO/IEC 15444-1 and Rec. ITU-T T.801 | ISO/IEC 15444-2. Improved context models will be introduced through an amendment.