//function to extract a tag from the string given in bcdata by tag ID
  function extract_tag(tag_id:PAnsiChar; abcdata:PAnsiChar;var rsltdata:PAnsiChar):integer;
  var
  bflen:integer;
  tslen:integer;
  stpos:integer;
  rfln:integer;
  s_len:string;
  eos:boolean;
  pp:PAnsiChar;
  begin
       writeln('TAG '+tag_id+' bcdata '+abcdata);
       writeln('String len in et '+IntToStr(strlen(abcdata)+1));
       tslen:=strlen(abcdata);
       if tslen = 0 then
          begin
               result:=-1;
               exit;
          end;
       eos:=false;
       stpos:=0;
       while (eos=false) do
             begin
                  pp:=Stralloc(4);
                  strlcopy(pp,@abcdata[stpos],3);
                  s_len:=StrPas(pp);

                  StrDispose(pp);
                  rfln:=StrToInt(s_len);
                  writeln('FLEN '+tag_id+' bcdata '+abcdata);
                  if ((rfln=0) or (stpos > tslen)) then
                     begin
                          eos:=true;
                          result:=-1;
                          exit;
                     end;
                  if (rfln > tslen) then
                     begin
                          eos:=true;
                          result:=-1;
                          exit;
                     end;
                  //ok if we are here we compare the tag id with the extracted one
                  pp:= stralloc(3);

                  strlcopy(pp,@abcdata[stpos+3],2);
                  if strlicomp(tag_id,pp,2) = 0 then
                     begin
                          strlcopy(rsltdata,@abcdata[stpos+5],rfln);
                          eos:=true;
                          result:=0;
                     end
                     else
                     begin
                          stpos:=stpos+rfln+5;
                          //advance to next field
                     end;


             end;
  end;