A. All calibrated volumetric glassware requires that the user be informed whether the ware is “To Contain” or “To Deliver” and is permanently marked “TC” or “TD”. When the graduation line denotes the volume contained in the calibrated vessel, it is marked TC. The ware is marked TD when the graduation line indicates the volume delivered from the vessel. TD calibrated vessels are different from the TC calibrated vessels because of the drainage holdback error. For example, when the amount of water required to wet the inner surface of the vessel in contact with the water is added to the TC volume. The TD vessel then delivers the same volume as the contained volume in a TC vessel. The International Standards Organization designation for “To Contain” is “IN” and the “To Deliver” is “EX”.