/usr/share/plplot5.13.0/tcl/cmap1a.pal is in plplot-tcl 5.13.0+dfsg-6ubuntu2.
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
4 #5500ff 00 #010005 44 #050000 55 #ff0000 100