anchor.diff:    integer, parameter :: XC_D10300 =  82
     integer, parameter :: XC_D00400 = 112
   
  -! tau mgga
  +! seven-variable derivatives up to order 4
   ! so far only linear response
  -! list under construction ...
     integer, parameter :: XC_D0000000 =  1
     integer, parameter :: XC_D1000000 =  2
     integer, parameter :: XC_D0010000 =  4
  
positive.code:   integer, parameter ::  XC_LDA  = 0
    integer, parameter ::  XC_GGA  = 1
    integer, parameter ::  XC_MGGA = 2
  ! Indices into the output array of derivatives. Fortran numbering.
    integer, parameter :: XC_D0 = 1
    integer, parameter :: XC_D1 = 2
    integer, parameter :: XC_D2 = 3
  
  ! all lda derivatives up to order 4
    integer, parameter :: XC_D00 =  1
    integer, parameter :: XC_D10 =  2
    integer, parameter :: XC_D01 =  3
  
negative.code: module xcfun
    use xcfun_autogen
    implicit none
  
  ! these parameters should mirror those in xcfun.h
    integer, parameter ::  XC_VARS_A  = 0
    integer, parameter ::  XC_VARS_N  = 1
    integer, parameter ::  XC_VARS_AB = 2
  