This attribute is defined by the OASIS Open Exchange Table Model. Either proportional measure of the form number*, e.g., “5*” for 5 times the proportion, or “*” (which is equivalent to “1*”); fixed measure, e.g., 2pt for 2 point, 3pi for 3 pica. (Mixed measure, e.g., 2*+3pt, while allowed in the full CALS table model, is not supported in this Exchange model.) Coefficients are positive integers or fixed point numbers; for fixed point numbers, a leading (possibly 0) integer part is required, and implementations should support at least 2 decimal places. A value of "" [the null string] is treated as a proportional measure of “1*”.
The fixed unit values are case insensitive. The standard list of allowed unit values is “pt” (points), “cm” (centimeters), “mm” (millimeters), “pi” (picas), and “in” (inches). The default fixed unit should be interpreted as “pt” if neither a proportion nor a fixed unit is specified.