As the name suggests, this is where the majority of mares are registered. Thoroughbred mares and imported mares from other warmblood breeds must score sufficiently to enter the Main Stud Book or they will not be accepted. An overall mark of at least 7 for these mares with no mark in any section lower than 5 is considered an acceptance.
Hanoverian mares may receive an overall mark of at least 6 with no section lower than 5 to gain acceptance in the Main Stud Book. Hanoverian mares must also be out of dams which are registered in the Main Stud Book or Stud Book. The sire of the mare as well as the sires of the dam, the grandam and the great-grandam on the dam's side either have to be registered in the Stallion Book of the Hanoverian Society or come from breeding populations which fulfil the requirements and meet the aims as laid down in the breeding program of the Verband hannoverscher Warmblutzuchter.
For a stallion to be considered for licensing, the dam as well as her own dam must be registered in the Main Stud Book, the great-grandam on the dam's side must at least be registered in the Stud Book.
e.g.
SIRE 1st Generation 2nd Generation 3rd Generation 4th Generation DAM Dam's Sire Grandam's Sire Great-Grandam's Sire (Main Stud Book or Stud Book)