ECHO, also XNS is written in the Fortran90 programming language. The reader is referred to the above cited paper for full derivation of the GRMHD equations, and for the full description of the XCFC solvers.</p>
<p>The 4.0 version of XNS adds the possibility of solving for the structure of a magnetised, rotating NS in a class of theories of gravity alternative to general relativity (GR), that is massless scalar tensor theories (STTs). Moreover, support for the use of realistic, tabulated equations of state (