2.1.1210 Part 1 Section 188.8.131.52.1, alpha (Alpha)
a. The standard states that the val attribute specifies the opacity as expressed by a percentage value.
Office uses the val attribute to specify a percentage value for several elements.
b. The standard states that ST_PositiveFixedPercentage is read and written as a floating point value with a trailing percent sign.
Office will read in percentages formatted as floating point value with a trailing percent sign or as an integer 1000th of a percent without trailing percent sign, but only write out percentages as the latter.