(a) An agent has authority described in this article if the power of attorney refers to general authority with respect to the descriptive term for the subjects stated in section one hundred four through section one hundred seventeen of this article or cites the section in this article in which the authority is described.
(b) A reference in a power of attorney to general authority with respect to the descriptive term for a subject in section one hundred four through section one hundred seventeen of this article or a citation to a section of section one hundred four through section one hundred seventeen of this article incorporates the entire section as if it were set out in full in the power of attorney.
(c) A principal may modify authority incorporated by reference.