The Technical Note (TN) 36 SOFA subroutines and the Astronomical Almanac defined bias, precession, and nutation going from a celestial to a terrestrial reference frame. However, previous SOFA subroutines had seemed to define those quantities as from terrestrial to celestial, which was how the TN 32 USNO calculator defined those quantities.
So, to be consistent with TN 32, the bias, precession, and nutation are defined as going from terrestrial to celestial; i.e.,
y_GCRF = [B][PR][NU][GST][PM]*y_ITRF
where, y_ITRF is a position vector whose components are written in the ITRF frame, and
y_GCRS is a position vector whose components are written in the GCRF frame.
Note for reference purposes, the equation below is how the astronomical almanac defines those quantities:
y_ITRF = [PM][GST][NU][PR][B]*y_GCRF
So, in effect the EO matrix calculator definitions of [PM],[GST],[NU],[PR], and [B] are transposed from what the astronomical almanac publishes.
Please note the difference.