Text searching is achieved by techniques including phrase frequency analysis and phrase-co-occurrence analysis. The locking mechanism includes an operating member rotatable to the locking position and to the unlocking position. According to the apparatus and method, convenience in using the washing machine and the dryer together is further enhanced. The data in the memory device may include identification data, anti-arbitrage variables, usage data, maximum use values, and performance data related to the ink stick, and the coupler and memory device may employ various means for communicating this data. Alternatively, the droplet assistor may be a mechanical oscillator such as a piezoelectric transducer that generates oscillations in the ink sufficient to periodically form convex ink menisci across the nozzle outlets, but insufficient to cause ink droplets to separate from the outlets.