%N uvrdvr %F $MIR/src/subs/uvio.c
%D Return the value of a UV variable.
%P rjs
%: uv-i/o
%B
FORTRAN call sequence:
        subroutine uvrdvra(tno,varname,adata,adefault)
        subroutine uvrdvri(tno,varname,idata,idefault)
        subroutine uvrdvrr(tno,varname,rdata,rdefault)
        subroutine uvrdvrd(tno,varname,ddata,ddefault)
        subroutine uvrdvrc(tno,varname,cdata,cdefault)
        integer tno
        character varname*(*)
        character adata*(*),adefault*(*)
        integer   idata,    idefault
        real      rdata,    rdefault
        double precision ddata,ddefault
        complex cdata,cdefault

  These routines get the first value of a variable. If the variable is
  missing,the default value is returned.

  Input:
    tno         The handle of the uv data file.
    varname     The name of the variable to return.
    default     The default value.
  Output:
    data        The returned value of the variable.                     
