However, no testimony shall relate to unpublished material or information or to the reporters' motivations, bias, mental impressions, or other information extrinsic to what the reporter saw and heard, and the reporter shall not be obligated to reveal any confidential sources.
Reporters do not have to tell their political party.
The text say they do not have to reveal motivations or biases.
( z1 obligate :polarity - :ARG1 ( z2 person :ARG0-of ( z3 report ) ) :ARG2 ( z4 tell :ARG0 z2 :ARG2 ( z5 political-party :poss z2 ) ) )