IEEE FP8 Formats for Machine Learning (Draft) [pdf]

Formats, plural.

sign:explicit leading mantissa bit:mantissa bits:exponent bits

1:0:(P-1):(8-P) where P ∈ [1,7]

P ∈ [3,5] appears to be more useful

binary8p3 -> 1:0:2:5

binary8p4 -> 1:0:3:4

binary8p5 -> 1:0:4:3

Edge cases:

P = 8 would disallow all exponent bits, leaving a sign bit and 7 explicit mantissa bits of precision

P = 0 would be unsigned and 8 exponent bits with only an implicit precision bit but no explicit mantissa bits