Maybe it’s just general persnicketiness on my part, but why do $\mathrm{\mathcal{B}\mathcal{E}\mathcal{F}\mathscr{H}\mathcal{I}\mathcal{L}\mathcal{M}\mathcal{R}}$ appear (in Firefox and rekonq) in a different type than the letters $\mathrm{\mathcal{A}\mathcal{C}\mathcal{D}\mathcal{G}\mathcal{J}\mathcal{K}\mathcal{N}\mathcal{O}\mathcal{P}\mathcal{Q}\mathcal{S}\mathcal{T}\mathcal{U}\mathcal{V}\mathcal{W}\mathcal{X}\mathcal{Y}\mathcal{Z}}$? And how can I get a letter like $\mathbb{P}$ or $\mathbb{Q}$ to stand upright like $\mathrm{\mathbb{P}\mathbb{Q}}$ but by itself without getting italicized?

(Sorry for the new username. I lost my password and for some reason Yahoo can’t get mail from the forums.)

Perhaps you need to install the STIX fonts (see here for some slightly out-of-date, but still useful instructions).

I see those calligraphic letters all set in the same font. And, moreover $\mathbb{P}$ and $\mathbb{Q}$ are set upright (as, for that matter, are $\mathbb{A}$ and $\mathbb{b}$).

Alas, what *you* see is strongly-dependent on what fonts you have installed.

In more detail:

On my system, ℬ (U+212C) is available in `STIXGeneral`

, `Apple Symbols`

and `Arial Unicode MS`

. But 𝒜 (U+1D49C) is only available in `STIXGeneral`

. In current versions of Firefox, I believe the default value of `font.mathfont-family`

is

```
MathJax_Main, STIXNonUnicode, STIXSizeOneSym, STIXSize1, STIXGeneral, Asana Math, Symbol,
DejaVu Sans, Cambria Math
```

so the version in `STIXGeneral`

is what I see.

P.S.: Congratulations on figuring out how to make this page ill-formed! It took a bit of work to fix the issue.

I didn’t mean to do that, but you like to make the forum better and better, so all’s well that ends well, I hope…

With the STIX fonts, those letters do all look the same, in the curlier script. *** However, I think part of the problem is that the calligraphic BEFHIKLM live in a totally different area of Unicode than the other calligraphic letters. Your ”ℬ” at U+212C certainly doesn’t immediately follow the ”𝒜” at U+1D49C. The very next symbol after ”𝒜” is ”” (undefined), followed by ”𝒞” and ”𝒟”, because the Unicrats who designed these things in their infinite wisdom ensured that only a portion of the “calligraphic” alphabet was put in a different codepage on an alternate plane of existence, where some fonts may or may not even have glyphs, and the glyph may very well look different, because there is absolutely no assurance in Unicode of any consistency in the way fonts are going to be applied across such vastly different planes of the code space. Why isn’t it possible to put real ASCII letters in a calligraphic font? Seems like it should work but it doesn’t, in my browser anyways:

```
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1 plus MathML 2.0 plus SVG 1.1//EN"
"http://www.w3.org/2002/04/xhtml-math-svg/xhtml-math-svg.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head><title>Probability Space</title></head>
<body>
<math xmlns="http://www.w3.org/1998/Math/MathML">
<mfenced>
<mi>Ω</mi>
<mi mathvariant='script'>F</mi>
<mi mathvariant='double-struck'>P</mi>
</mfenced>
</math>
</body>
</html>`
```