/usr/share/gwyddion/gradients/Pm3d is in gwyddion-common 2.44-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | Gwyddion resource GwyGradient
0 0 0 0 1
0.166667 0.265412 0 0.564 1
0.333333 0.391234 0 0.831373 1
0.666667 0.764706 0 0 1
1 1 0.894118 0 1
|