RNPL
The code is written in a combination of Fortran and RNPL (Rapid Numerical Prototyping language), a language designed by Matt Choptuik and Robert Marsa: http://laplace.physics.ubc.ca/People/matt/Rnpl/
RNPL takes care of reading parameters, memory allocation, file i/o etc., and also provides a convenient mechanism for implementing finite difference discretizations of hyperbolic type equations (which in this particular code is for the scalar field matter source, and a couple of metric variables)