The value of prospective long-term studies on the features and course of multiple sclerosis is determined by the reliability with which relevant infor mation is documented. This involves two basic problems: I) The docu mentation system used must be detailed enough to provide adequate data on the essential features and course of the disease in a given case; on the other hand, it must not be so complicated and cumbersome as to preclude its use in the routine care of MS patients. 2) Since no system can fully anticipate new problems and scientific approaches that may become impor tant at some...