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OpenXML Spreadsheet Formulas Called into Question

Posted by Jonathan Allen on Jul 11, 2007

Sections: Enterprise Architecture,; Architecture & Design,; Development
Topics: .NET ,; Programming ,; OpenXML ,; Standardization ,; Office Business Applications

Rob Weir has called the spreadsheet formulas into question. Lost in the posturing and grandstanding are some serious holes in the specification.

The first example is the SIN function:

Description: Computes the sine of x.

Notice there is no mention of what units the parameter x expects. While you can figure out that it expect radians from the examples, it is never explicitly stated.

The next mistake cited by Rob Weir is quite amusing.

The AVEDEV function (Part 4, Section 3.17.7.17) should return the average deviation of a list of values. However, the formula given for this function is actually for calculating the number of combinations of n things taken k at a time. Nice formula, though. Jakob Bernoulli would be proud. But anyone using an OOXML spreadsheet application based on this standard will be perplexed at the values returned by their AVEDEV function. Did these formulas get any expert review in Ecma?

Internationalization also raises questions.

The CONVERT function (Part 4, Section 3.17.7.48) converts from one unit to another. Some conversions explicitly allowed include liquid measure conversions such as from liters to cups or tablespoons. But whose cup and whose tablespoon? Traditional liquid measures vary from country to country. In the US, a cup is 8oz, except for FDA labeling purposes when a cup is 240ml. But in Australia a cup is 250ml and in the UK it is 285ml. Similarly a tablespoon has various definitions. OOXML is silent on what assumptions an application should make. I guess I won't be using OOXML to store my recipes, and certainly not to calculate medical doses!

Rob Weir lists several more problems with the OpenXML spec in his blog An Antic Disposition.