2012-07-12 21:07, Asmus Freytag wrote:
What the examples show from TeX is that colon and ratio cannot be substituted for each other without affecting the display.
This looks like a problem in TeX rather than character standards. If TeX can space $a+b$ properly, what’s the issue with $a:b$? And when I tested it, I got proper spacing, corresponding to the example in “Detailtypographie” (which mentions that the colon, Doppelpunkt, is used “eventuell aus didaktischen Gründen, sonst eher veraltet oder als »verhält sic zu« verwendet”).
However, it might be argued that disambiguation is desirable, because COLON is also used as punctuation symbol in mathematical expressions, as in “f: A → B” and here (arguably) there should be some spacing after the colon but not before it. Yet, there are other contexts where the meaning of a symbol should affect is spacing in math, and yet we don’t have specialized symbols for them. (For example, the vertical bar should probably have different spacing when used for an absolute value, as in |a|, and when used as a separator as in {x|x²<1}, but this must be handled by special logic in typesetting software or, more reasonably, by using spaces and/or formatting tools.)
I have no opinion on ISO 80000-2, but if this example is typical, I don't think much of the quality of that standard.
It’s about notations, not typography, and it has some flaws, but I don’t see an issue here.
Yucca
