2.1.871 Part 1 Section 18.17.5.4, Interpretation

a.   The standard gives maximum value as 2^1023 - 1, minimum as - 2^1023 + 1.

Office uses maximum 2^1024 – 2^971, minimum - 2^1024 + 2^971 and has smallest positive value of 2^-1022.

b.   The standard does not specify behavior if the absolute value of the raw value is smaller than the smallest positive value in the value space.

In Office, if the absolute value of the raw value is smaller than the smallest positive value in the value space, then a consuming application shall treat this as equivalent to 0.