Commission Regulation (EC) No 1021/1999 of 18 May 1999 amending Regulations (EC) No 1666/98, (EC) No 1667/98, (EC) No 1735/98, (EC) No 1759/98, (EC) No 1760/98 and (EC) No 2198/98 opening standing invitations to tender for the export of barley held by certain intervention agencies.