When a public entity alters a facility in a way that affects, or could affect, how usable it is, the altered part must become readily accessible and usable as far as feasible. If the altered area holds a primary function (a major activity the facility exists for; mechanical rooms, corridors, entrances and ordinary restrooms do not count), the entity must also make accessible the route by which people reach that area, plus the restrooms, phones and fountains that serve it, spending up to 20 percent of the primary function work's cost; beyond that the spend is disproportionate and the entity provides what the 20 percent buys in priority order (entrance first, then route, restroom, phones, fountains, then parking, storage and alarms). Alterations on one route within three years are added together so the duty cannot be dodged with small jobs. Historic properties comply as far as feasible, with alternative access under 35.150 where physical access would harm their significance. Elements already built to the 1991 Standards or UFAS before 15 March 2012 are safe-harboured against incremental 2010 changes.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.