A saw sheath is provided which allows a saw to be inserted easily and smoothly, which prevents the inserted saw from easily falling out or rattling in the sheath, and which can suppress scraping-off of the inner wall by the blade tip of the saw blade caught by the inner wall. According to the present invention, CO2, which has conventionally been discharged, is returned to the steam reformer and is used effectively to produce DMC, and also devices for producing methanol and DMC can be simplified. The present invention further relates to methods for treating cancer, such as leukemia or lymphoma, using an arsenic sulfide compound. The CIMOM also decomposes a client query to determine the appropriate source or sources of information necessary to resolve that query, and further handles client queries having inherited object classes to render appropriate results in a uniform manner.