Is set if: For the current root-element sub-root-objects exists.
Effect if set:
For the current root-element sub-root-objects are given (see section 21.2.7 on page ) and the offset, at which byte they start in the root-element.
If not set: For the current root-element no sub-root-objects exists.
Effect if not set:
No offset is given for the sub-root-objects in the current root-element and no sub-root-objects are given in the current root-element.