anchor.diff:  ! ================================================================================================ !
  +!
  +!  Read a beam distribution
  +! ~~~~~~~~~~~~~~~~~~~~~~~~~~
  +!
   !  A. Mereghetti and D. Sinuela Pastor, for the FLUKA Team
   !  V.K. Berglyd Olsen, BE-ABP-HSS
  -!  Last modified: 2018-10-30
  -!  Read a beam distribution
  +!  Last modified: 2019-07-09
   !
  -!  Format of the input file:
  +!  Format of the original DIST input file:
   !    id:         unique identifier of the particle (integer)
   !    gen:        parent ID (integer)
   !    weight:     statistical weight of the particle (double: >0.0)
  
positive.code: !  NOTA BENE:
  !  - id, gen and weight are assigned by the fluka_mod_init subroutine;
  !  - z and zp are actually useless (but we never know);
  !  - in case the file contains less particle than napx, napx is re-assigned
  !
  ! ================================================================================================ !
  module mod_dist
  
negative.code:     call dist_appendFormat(dist_fmtPX, one)
    case("PY/P0","PYP0") ! Relative vertical momentum
      call dist_appendFormat(dist_fmtPY, one)
    case("SIGMA") ! Longitudinal relative position
      call dist_unitScale(fmtName, fmtUnit, 1, uFac, fErr)
      call dist_appendFormat(dist_fmtSIGMA, uFac)
    case("DT") ! Time delay
  