It consists of four parts, sign, regime, exponent and fraction (also known as significand/mantissa). Each 64-bit MMX register corresponds to the mantissa part of an 80-bit x87 register. The floating point values are represented using three separate values, mantissa, exponent, and sign. Note that the exponent's lowest bit is intentionally allowed to propagate into the mantissa. The mantissa is expressed as a binary fraction in IEEE base-two floating point formats. Each value is then truncated to an 8-bit mantissa (fractional part). This allows a table of logarithms to include only one entry for each mantissa. The fractional part is known as the mantissa. Such a range would cover all possible values of the mantissa. The description was published in 1767 in "Mantissa plantarum". A second book is known as the "Supplement to On the Soul" ("Mantissa"). Later fictional works include "The Ebony Tower", "Daniel Martin", "Mantissa", and "A Maggot".