%N wrhdr %F $MIR/src/subs/headio.c
%D Write a real valued header variable.
%P pjt
%: header-i/o
%B
FORTRAN call sequence:
        subroutine wrhdr(tno,keyword,value)
        integer tno
        character keyword*(*)
        real value

  This writes a real-valued header keyword.
  Input:
    tno         Handle of the data set.
    keyword     Name of the keyword to write.
    value       The value of the keyword.                               
