Vertical alignment of prime

[ronkok]

In a TeX expression such as $f_c'$, the prime is treated as a superscript. A prime can be rendered using character ′, U+2032. But the bottom of the ink in that glyph is higher than in characters used in other superscripts, such the "2" used in $x^2$.

If I place U+2032 into the second child of a <msup> element, Firefox lowers the glyph so that the prime is at the correct vertical alignment. At this date, Chrome Canary does no such adjustment.

Which behavior is correct? MathML-Core is silent on this question. I think the standard behavior should be spelled out.

[fred-wang]

This is tracked by issue #135 but we decided won't be in level 1.

[ronkok]

The delay is unavoidable, I suppose. Regrettable, though. Some documents written to the current spec will break when a future spec change occurs.

#135 speaks mostly about size changes that relate to script level. It does not explicitly mention prime vertical alignment, so I'll leave this issue open.

[ronkok]

I withdraw my comment about future breaking documents, and I'm sorry if I sounded peevish. I've come up with a reasonable workaround.

I do think level 2 should use the ssty variant glyph for U+2032.