Tweaking lib/symbols for XML entities

[Guenter Milde]

Dear Thibaut,

On 2020-05-10, Thibaut Cuvelier wrote:

> In order to ensure a valid DocBook entity with math formulae, the MathML
> generator must produce valid XML. Right now, it "only" produces valid HTML
> (which is already quite an achievement!). The difference is in the
> entities: in HTML, you can use many entities, like ∑. This is no more
> the case in XML, where you have to define all entities (that is, besides
> <, >, &, ", '). A solution for DocBook would be to
> define the needed entities in the XML document, but that would require
> generating all math formulas, remembering the needed entities, then output
> the mapping at the *beginning* of the XML document.

Why don't you simply use Unicode literal characters?

Günter