As a professional courtesy, GAO will inform requesters of substantive media inquiries during an ongoing assignment.
( ( As ( a ( professional courtesy ) ) ) ( , ( GAO ( ( will ( ( inform ( requesters ( of ( substantive ( media inquiries ) ) ) ) ) ( during ( an ( ongoing assignment ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN As) (NP (DT a) (JJ professional) (NN courtesy))) (, ,) (NP (NNP GAO)) (VP (MD will) (VP (VB inform) (NP (NP (NNS requesters)) (PP (IN of) (NP (JJ substantive) (NNS media) (NNS inquiries)))) (PP (IN during) (NP (DT an) (JJ ongoing) (NN assignment))))) (. .)))
GAO will never inform requesters of substantive media inquiries during an ongoing assignment. 
( GAO ( ( ( will never ) ( ( inform ( requesters ( of ( substantive ( media inquiries ) ) ) ) ) ( during ( an ( ongoing assignment ) ) ) ) ) . ) )
(ROOT (S (NP (NNP GAO)) (VP (MD will) (ADVP (RB never)) (VP (VB inform) (NP (NP (NNS requesters)) (PP (IN of) (NP (JJ substantive) (NNS media) (NNS inquiries)))) (PP (IN during) (NP (DT an) (JJ ongoing) (NN assignment))))) (. .)))