Generally, a genealogical DNA test might use either autosomal STRs or autosomal SNPs. (STR's are Short Tandem Repeats; SNPs are single-nucleotide polymorphisms.) However, testing companies do not currently offer autosomal STRs tests that use enough STR markers for genealogy.
The schema is the Active Directory component that defines all the objects and attributes that the directory service uses to store data. The physical structure of the schema consists of the object definitions. The schema itself is stored in the directory.
The schema object lets administrators extend or modify the schema when necessary. However, because each schema object is integral to the definition of Active Directory objects, deactivating or changing these objects can fundamentally change or disrupt a deployment.