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.
Active Directory is Microsoft's trademarked directory service, an integral part of the Windows 2000 architecture. Like other directory services, such as Novell Directory Services , Active Directory is a centralized and standardized system that automates network management of user data, security, and distributed resources, and enables interoperation with other directories. Active Directory is designed especially for distributed networking environments.