These are most commonly used on wheelchair ramps and edges of platforms. These are not required, but suggested. The material used to provide contrast shall be an integral part of surface. Once again these are suggestions. Environments are multi-dimensional feedback systems that guide, inform, and govern individuals.
Current literature proposes that a discrepancy analysis of skills within environments be conducted.
This involves an analysis of skills needed to move and be oriented in an environment, then identification of errors that can be attributed to failure to respond to natural cues. The relevant cues and their salient features are then identified. Salient features are those with sufficient magnitude and immediacy to be of use. These salient features can then be adapted to make the environment more accessible. Relevant cue discrimination may use either configurational or compound cues.