Vyšel draft IETF pkix - Clearance Attribute and Authority Clearance Constraints Certificate Extension
This document defines the syntax and semantics for the Clearance
attribute and the Authority Clearance Constraints extension in X.509
certificates. The Clearance attribute is used to indicate the
clearance held by the subject. The Clearance attribute may appear in
the subject directory attributes extension of a public key
certificate or in the attributes field of an attribute certificate.
The Authority Clearance Constraints certificate extension values in a
Trust Anchor (TA), CA public key certificates, and an Attribute
Authority (AA) public key certificate in a public key certification
path constrain the effective Clearance of the subject.