A knowledge market may have some structure. it may ,for instance,be organized around a specific area of interest (such as web development, tax accounting practices,etc.). But the knowledge usually is not specific to a unit or functional area. Therefore, it does not affect an individual's job in any formal way. Its use is not a rourine required practice (i.e., use is ad hoc),and typically, each piece of knowledge is not reused as extensively as in a knowledge hierarchy . Because users are often from defferent units, the knowledge typically is not custom-fitted to a user's context. Instead ,each user must contextualize the knowledge for his or her own environment and purposes.