OptionalchildThe child space (chOff/chExt), in pixels: what the members' anchors are stated in,
mapped onto the group's frame by a scale per axis. Absent, the group's frame at the origin.
OptionaleffectsThe group's effects (grpSpPr/effectLst).
OptionalextExtension lists kept as the file states them, by the element each extends.
OptionalfillThe fill members that take the group's fill draw with (grpSpPr). A nested group may itself
take its group's fill.
OptionalhoverThe hyperlink followed on hover (cNvPr/hlinkHover).
OptionalhyperlinkThe hyperlink on the whole group (cNvPr/hlinkClick).
OptionallocksEdit locks (grpSpLocks) by the file's own names: noGrp, noUngrp, noSelect, noRot,
noChangeAspect, noMove, noResize.
OptionalmembersThe members in z-order. A member is an ordinary movable whose anchor is absolute in the
child space: anchor.tl its top-left and anchor.br its size, with no cells.
OptionalnameThe name of the group.
Optionalscene3dThe 3-D scene (grpSpPr/scene3d) as the file states it: an opaque DrawingML fragment.
OptionalsourceThe id the file gave the group (cNvPr/@id). Kept and written again, as a shape's is.
OptionaltitleThe title (cNvPr/@title), beside the description.
A JSON representation useful for persistence.