Identification: before starting work at a site, each employer must have a competent person identify every confined space where employees it directs may work and decide which are permit spaces, evaluating each space and testing as necessary. Warning and exclusion: an employer that identifies or is told of a permit space must warn exposed employees with danger signs or an equally effective method (similar wording to "DANGER, PERMIT-REQUIRED CONFINED SPACE, DO NOT ENTER" suffices), and must also notify, in a timely way and by a method other than posting, the controlling contractor and its employees' authorized representatives of where the space is and what danger it poses. If that employer has not authorised its employees to work in the space, it must take effective steps to keep them out. Any employer deciding its employees will enter must implement a written permit space program meeting 1926.1204 at the site and make it open to inspection by employees and their representatives before and during entry. Alternate procedures (e): an employer may skip 1926.1204 to 1926.1206 and 1926.1208 to 1926.1211 only if it can show all physical hazards are eliminated or isolated by engineering controls so the sole hazard is atmospheric, and that continuous forced air ventilation alone keeps the space safe with safe exit if ventilation fails; monitoring and inspection data must support both showings, any initial data-gathering entry follows the full program, and the determinations and data are documented and available to entrants. Entry then requires removing unsafe cover conditions first, guarding the opening, pre-entry testing using a calibrated direct-reading instrument, checking oxygen, then flammables, then toxics, with entrants able to observe; no hazardous atmosphere while anyone is inside; forced air from a clean source directed at occupied areas until all have left; continuous monitoring (or periodic where continuous equipment is not commercially available or periodic is sufficient); immediate exit and evaluation if a hazard appears; a safe entry and exit method, with job-made hoists approved in writing by a registered professional engineer; and a written, dated, signed certification before entry. Reclassification: a competent person re-evaluates a non-permit space when use or configuration changes may raise hazards; a permit space becomes non-permit only when there are no atmospheric hazards and all hazards are eliminated or isolated, without entry unless that is infeasible (ventilation is not elimination), documented by a dated, signed certification, with re-evaluation if hazards return. Coordination: the host employer, before entry begins, gives the controlling contractor the information it has on each known permit space's location, its hazards or why it qualifies as a permit space, and precautions previously used by the host or earlier contractors. The controlling contractor, before entry, obtains that host information and passes to each entering entity and to any entity whose work could create a hazard in the space the host information, its own additional information on those subjects, and precautions used by host, contractor or other entry employers. Each entry employer, before entry, obtains the controlling contractor's information and tells the controlling contractor which permit space program it will follow and the hazards it expects to meet or create. The controlling contractor and entry employers coordinate when more than one entity enters at the same time or when other hazard-creating activities run concurrently. After entry, the controlling contractor debriefs each entering entity, each entry employer reports its program and hazards met or created in a timely manner, and the controlling contractor passes this to the host employer. Neither host nor controlling contractor must enter a space just to collect information unless it has employees in it. Where no controlling contractor is present, the host employer or the employer arranging the entry work fills that role.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.