ZF_TYPE = c("tail correlation function", "positive definite",
"negative definite", "process",
"method for Gauss processes", "method for Brown-Resnick processes",
"shifted shape function",
"distribution family", "shape function", "trend", "interface",
"undefined", "other type")
ZF_DOMAIN = c("single variable", "kernel", "calling model", "mismatch")
ZF_ISOTROPY = c("isotropic", "space-isotropic", "zero-space-isotropic",
"vector-isotropic", "symmetric", "cartesian system",
"earth system", "spherical system", "cylinder system",
"non-dimension-reducing", "parameter dependent",
"")
ISOTROPIC
gives the numerical code for option
"isotropic"
SPACEISOTROPIC
gives the numerical code for option
"space-isotropic"
CARTESIAN_COORD
gives the numerical code for option
"cartesian system"