Additional special character support is needed for representation of units of measure

[ElisaKendall]

At a minimum, these include all upper and lower case Greek alphabet, the degree symbol (i.e., "°"), the percent symbol (i.e., "%"), and the multiplication symbol commonly used in units symbols (i.e., "⋅"). The ability to represent superscripts and subscripts, and to allow italics will also be needed for representation of units. The rules that disallow special characters should be updated to allow for such units symbols. Important examples include the seven defining constants and their symbols for the SI system of units, specified at https://www.bipm.org/en/measurement-units/si-defining-constants, UCUM measurement units, including symbols, specified in section 4 of https://ucum.org/ucum.html and referenced by the U.S. National Institutes of Health at https://ucum.nlm.nih.gov/, as well as in ISO 11240, which is one of the standards we need to support for the IDMP project.

Other math symbols may be required as well for the representation of measurement-specific equations, but allowing these would be a good starting point. See the current set of errors in the quantities and units ontology produced by the hygiene testing for examples.

Note that these issues will also occur in FIBO when we implement units for commodities contracts.

[mereolog]

First, if we are going to go beyond the ASCII set, then we should probably use UTF-8 codes in hygiene sets - perhaps using some ranges or something similar.
Secondly, we should be careful with using different symbols that look the same or very similar, like different kinds of hyphens. Using these may open door to a syntactical mess.
Finally, I would prefer if we keep the chars to the ASCII set if possible. For instance, can we use '*' or 'x' instead of "⋅".

[ElisaKendall]

@merelog - I agree about UTF-8 for sure. And I'm also in agreement about things like hyphens, which is why I suggested that we only add a limited number of symbols that we know are required for quantities, including Greek letters, %, the degree symbol, etc. For multiplication, I'll change to asterisk in the quantities ontology, but if we end up using something from UCUM or SI, etc. and generate it, then we'll have to add an automated conversion from the dot to "*".