The name of a trust point assigned to the proxy
service. The trust point contains information that
can be used for certificate enrollment or for importing
keys and certificates.
A trust point may also contain identifying information
about keys and certificates, and the path and the
protocol to be used for the proxy device to
communicate with a Certificate Authority which
issues certificates for the proxy service.
If no trust point is assigned to the proxy service,
the name will be a NULL string.