This is a preferred convenience directive that combines
%HTML.AllowedElements and %HTML.AllowedAttributes.
Specify elements and attributes that are allowed using:
element1[attr1|attr2],element2.... For example,
if you would like to only allow paragraphs and links, specify
a[href],p. You can specify attributes that apply
to all elements using an asterisk, e.g. *[lang].
You can also use newlines instead of commas to separate elements.
Warning:
All of the constraints on the component directives are still enforced.
The syntax is a subset of TinyMCE's valid_elements
whitelist: directly copy-pasting it here will probably result in
broken whitelists. If %HTML.AllowedElements or %HTML.AllowedAttributes
are set, this directive has no effect.