14 CFR Parts 382 and 399; 49 CFR Part 27 - Nondiscrimination on the Basis of Disability in Air Travel: Accessibility of Web Sites and Automated Kiosks at U.S. Airports

(iv) Function keys. Function keys must comply with paragraphs (k)(6)(iv)(A) and (B) of this section.

(A) Contrast. Function keys must contrast visually from background surfaces. Characters and symbols on key surfaces must contrast visually from key surfaces. Visual contrast must be either light-on-dark or dark-on-light. However, tactile symbols required by (k)(6)(iv)(B) are not required to comply with paragraph (k)(6)(iv)(A) of this section.

(B) Tactile symbols. Function key surfaces must have tactile symbols as follows: Enter or Proceed key: raised circle; Clear or Correct key: raised left arrow; Cancel key: raised letter ex; Add Value key: raised plus sign; Decrease Value key: raised minus sign.