2.1.1772 Part 4 Section 188.8.131.52, ST_TextSpacingPercent (Text Spacing Percent)
a. The standard states that the ST_TextSpacingPercent simple type specifies the range that the spacing percent in terms of line in hundredths.
Office uses this type to specify the percent of a line height in thousands of a percent.
b. The standard states that ST_TextSpacingPercent is read and written as a percent with a trailing percent sign.
Office will read in percentages formatted with a trailing percent sign or as 1000th of a percent without trailing percent sign, but only write out percentages as 1000th's of a percent without trailing percent sign.