Specifies a person´s home organization using the domain name of the organization.
https://wiki.refeds.org/display/STAN/SCHAC+Releases 

Notes on usage:

Contrary to scoped attributes (eduPersonScopedAffiliation, eduPersonPrincipalName) the Shibboleth Service Provider software (before version 2.6) does not perform any checks on what Identity Provider may issue what schacHomeOrganization value. Also note that other SAML implementations do not perform such checks by default (or at all), for any kind of attribute.