anchor.diff:  
   uses
     Classes, contnrs, sysutils,
  -  mVirtualDataSetInterfaces, mMaps, mVirtualFieldDefs, mLog;
  -
  -const
  -  PREFIX_JOIN_SEPARATOR = '$';
  +  mVirtualDataSetInterfaces, mMaps, mVirtualFieldDefs, mLog, mFieldNames;
   
   type
     TBuildExternalEntityKeyFromDatumFunction = function (aSource : IVDDatum): string of object;
  
positive.code: begin
    aPrefix := '';
    aFieldName := aSource;
    i := Pos(PREFIX_JOIN_SEPARATOR, aSource);
    if i > 0 then
    begin
      aPrefix := Copy(aSource, 1, i);
  
negative.code: begin
    if FPrefix=AValue then Exit;
    FPrefix:=Uppercase(AValue);
    if Copy(FPrefix, Length(FPrefix), 1) <> SEPARATOR_FIELDS_FROM_JOIN then
      FPrefix := FPrefix + SEPARATOR_FIELDS_FROM_JOIN;
  end;
  
  constructor TmBuiltInJoin.Create;
  