Re: Html character entities

On Tue, Feb 06, 2007 at 02:34:07PM -0600, Dave Hall wrote:
> On Tue, Feb 06, 2007 at 02:18:16PM -0600, Conrad Knauer wrote:
> > On 2/6/07, Keith Brown <brownk@chem4823.usask.ca> wrote:
> >
> > >Greek letters and a few math symbols. If I use "&rho;" (or the numerical
> > >equivalent) I can see it using Firefox on my laptop and one of my office
> > >machines (both Slackware 11) but not using Firefox on my other office
> > >machine or my home machine (both Slackware 10.2). The web explanations of
> > >these things are confusing and obtuse to say the least.
> > >
> > > Can anyone supply a simple explanation of these things ... a sort of
> > >"Character entities for dummies" type of thing? What can I do to get them
> > >working on the machines that currently don't display them or, more
> > >importantly, on the machines of those will be viewing these web pages?
>
> Conrad is close. To start, you need to select a character set that includes
> the characters you want displayed, utf-8 is certainly not what you want
> for greek or math sybmols. With the desired character set specified, you
> are then at the mercy of the browser understanding the particular entities
> you use and the visitor having that character set available to them.

HTML character entities are there to get around character encoding
problems; specifying an entity should be exactly identical to placing
that entity's character in a document if that document's encoding
included said character. The encoding shouldn't matter to how the
entities are understood by the browser. Of course, just because an
entity is defined in an HTML standard does not mean that it will be
understood by all browsers. This is the first issue, which is not likely
to be a problem if you're testing under firefox on multiple platforms.

The bigger problem is, mapping those entities to characters in fonts for
display. Not all users will have fonts with sensible greek characters,
and linux installations vary greatly in what fonts are installed and how
their character mappings are handled. Short story: Check to make sure
you've got math and greek fonts installed on the home and secondary
office machines. This doesn't mean anyone else will be able to see them,
though.

>
> If accurate rendering is important, then I'd say use something other than
> a web page (like a PDF document or a graphic).
>

Definitely. As an alternative that's getting better, MathML is gaining
more and more support.

See http://www.mozilla.org/projects/mathml/fonts/ for resources that are
useful for both HTML and MathML font problems.

-Jim
Received on Tue Feb 6 16:02:40 2007