ADDITIONAL_SECTIONS (Optional)
4 bytes: BlockSeparator - Value of 0 (To disambiguate from the INDEX block if not present)
4 bytes: NumAdditionalSections - Number of additional sections
''NumAdditionalSections ADDITIONAL_SECTION_ENTRY elements''
Each additional block must be in the format described above in ADDITIONAL_SECTION_ENTRY.
The block separator in the ADDITIONAL_SECTIONS header is so the MAR reader code knows whether it is reading an additional block or if it is reading the INDEX.IndexSize.
The Block identifier is a value used to uniquely identify additional blocks so that they may be optionally added in any order.