TElPolicyMappingsExtension is a descendant of TElCustomExtension class.
The following paragraph is taken from RFC 2459 (Housley, et. al.), part 18.104.22.168:
«This extension is used in CA certificates. It lists one or more pairs of OIDs; each pair includes an issuerDomainPolicy and a subjectDomainPolicy. The pairing indicates the issuing CA considers its issuerDomainPolicy equivalent to the subject CA's subjectDomainPolicy.
The issuing CA's users may accept an issuerDomainPolicy for certain applications. The policy mapping tells the issuing CA's users which policies associated with the subject CA are comparable to the policy they accept.
This extension may be supported by CAs and/or applications, and it MUST be non-critical.»