  Project X is a multi-megawatt proton facility being developed to support a
world-leading program in Intensity Frontier physics at Fermilab. The facility
is designed to support programs in elementary particle and nuclear physics,
with possible applications to nuclear energy research. A Functional
Requirements Specification has been developed in order to establish performance
criteria for the Project X complex in support of these multiple missions, and
to assure that the facility is designed with sufficient upgrade capability to
provide U.S. leadership for many decades to come. This paper will briefly
review the previously described Functional Requirements, and then discuss their
recent evolution.
