FUNCTION COPY({   FROM	  } THIS : MSTRING ;
	      {STARTING AT} POSN : INTEGER ;
	      {# OF CHARS } LEN  : INTEGER ): DSTRING;
{
EXAMPLE:
   NEW := COPY(NBUF, NAME_ADDR, NAME_LEN);
   NEW := COPY(NAME,5,12);
   NAME := COPY(NAME,2,3);

REQUIRES THE FOLLOWING GLOBAL DEFINITIONS:
   CONST
	  DEFAULT = 80; << DEFAULT line length >>
	  SMAX	  = 255; << MAXIMUM LENGTH OF A STRING >>
   TYPE
	  DSTRING = STRING DEFAULT;
	  MSTRING = STRING SMAX;
}
VAR	ix   : 1..SMAX;
	dest : DSTRING;
begin
  setlength(dest,0);
  If ( (len+posn) > DEFAULT ) then
    { return argument string unchanged since the argument string
      may be the destination string also. }
    dest := THIS
  else begin
    If ( (len+posn-1) <= length(this) )
      and (len > 0) and ( posn > 0) then
	for ix:=1 to len do
	  append( DEST, THIS[posn+ix-1])
  end;
  COPY := dest
end {of COPY};
en