An adjustable height tool for locating a magnetically readable and settable valve implanted in a living being. In one embodiment, the apparatus comprises a mechanical positioner and first and second stops. 5 to 8 threadscm and having a linear density of at least 50 dtex, with the second set of threads being transverse to the first set of threads, and wherein the ratio of the linear density of the first set of threads to the linear density of the second set of threads is >4. By maintaining and referencing a session context indicative of previous messages, an application identifies an atomic message as corresponding to a particular session context, and employs the session context to process the message within the context, or environment, defined by the previous messages in the session.