/usr/share/doc/texlive-doc/fonts/fontinst/examples/mathptm/zrhax.mtx is in texlive-font-utils 2013.20140215-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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\metrics
% This metrics file is loaded after having read the Times-Roman
% glyphs. We unset those glyphs that should be taken from cmr.
\unsetglyph{plus}
\unsetglyph{equal}
\unsetglyph{parenleft}
\unsetglyph{parenright}
\unsetglyph{bracketleft}
\unsetglyph{bracketright}
\endmetrics
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