The name of the file storing the issuer certificate.
It is a unix style '/' seperated string representing
the absolute path of the file in the file system of
the device. If there is no issuer certificate obtained
yet, the value of this object will be a zero length
string.
This object gets its non-zero length string value
after a successful 'caauth' PKI support action
triggered on the object cpkiAction.
This object gets set to zero length string when the
issuer certificate is deleted through a successful
'cadelete' action triggered on the object
cpkiAction.