who are not legally or contractually obliged to follow them, but the prevalence of diving accidents is known to be strongly correlated to human error, which is more common in divers with less training and experience. The Doing It Right philosophy of technical diving is strongly supportive of common standard procedures for all members of a dive team, and prescribe the procedures and equipment configuration that may affect procedures to the members of their organisations. The terms diving skills and diving procedures are largely interchangeable, but a procedure may require the ordered application of several skills, and is a broader term. A procedure may also conditionally branch or require repeated applications of a skill, depending on circumstances. Diver training is structured around the learning and practice of standard procedures until the diver is assessed as competent to apply them reliably in reasonably foreseeable circumstances, and the certification issued limits the diver to environments and equipment that are compatible with their training and assessed skill levels. The teaching and assessment of diving skills and procedures is often restricted to registered instructors, who have been assessed as competent to teach and assess those skills by the certification or registration agency, who take the responsibility of declaring the diver competent against their assessment criteria. The teaching and assessment of other task oriented skills does not generally require a diving instructor. There is considerable difference in the diving procedures of professional divers, where a diving team with formally appointed members in specific roles and with recognised competence is required by law, and recreational diving, where in most jurisdictions the diver is not constrained by specific laws, and in many cases is not required by law to provide any evidence of competence. Routine diving procedures These are the procedures that the diver uses during the course of a planned dive, where everything goes to plan, and there are no contingencies. Consequently, experienced divers tend to become expert in these procedures due to adequate practice. Some procedures may seldom be needed, or only be relevant to specific equipment, which is not often used, so refresher exercises are frequently required before dives using unfamiliar equipment, unusual tasks or unfamiliar conditions are expected. Dive planning, the pre-dive briefing. and selection, inspection, preparation and pre-dive checking of diving equipment, may be considered diving procedures, as they are essential parts of the normal diving operation, though they are done before