Ratiometric FRET indices. A = acceptor bleedthrough correction, acceptor bleedthrough coefficient, acceptor-only sample, or acceptor channel, depending on the column heading. D = donor bleedthrough correction, donor bleedthrough coefficient, donor-only sample, or donor channel, depending on the column heading. F = FRET channel. Inter = intermolecular biosensor design. Intra = intramolecular biosensor design. An equal sign means “equivalent”. M = monotonic. L = linear. P = proportional. IL = inversely linear. NA = not applicable.