Some embodiments of the invention provide a system for monitoring liquid consumption at one or more establishments. The barrel is received in the base and is connected with the base. The frequency synthesis circuit generates the output clock at a frequency under the control of a frequency select word that indicates the number of clock phases between successive clock edges. The substrate may be substantially planar and the partitions may be oriented to form a focused grid. Although the data nodes and clock nodes are at different potentials, the latch has reduced static power dissipation. For coding efficiency, the display time difference may be encoded using a variable length coding system or arithmetic coding.