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+# Internal MathML tests
+
+The web-platform-tests Project provides [MathML tests](https://github.com/web-platform-tests/wpt/tree/master/mathml/)
+for the [MathML Core](https://w3c.github.io/mathml-core/) specification. This
+directory contains tests for [MathML3](https://www.w3.org/TR/MathML3/) features
+implemented in Gecko or for Gecko-specific behaviors that are not described in
+any specification:
+
+- `disabled/`: Tests for MathML handling when support is disabled. This is
+  mostly used for Tor browser's "high security" mode, see
+  [bug 1173199](https://bugzilla.mozilla.org/1173199).
+
+- `fonts`: font-related tests, such as OpenType features not handled yet in
+  MathML Core or other Gecko-specific behavior.
+
+- `mathml-console-messages.html`: Tests for Gecko-specific console warning and
+  error messages triggered by MathML markup.
+
+- `mathspaces_names`: Tests for
+  [MathML3 namedspaces](https://www.w3.org/TR/MathML3/chapter2.html#type.namedspace)
+  which are removed from MathML Core. See
+  [bug 1793549](https://bugzilla.mozilla.org/1173199).
+
+- `mathvariant`: Tests for the
+   [mathvariant attribute](https://www.w3.org/TR/MathML3/chapter3.html#presm.commatt),
+   which is reduced to the case `<mi mathvariant="normal">` in MathML
+   Core. See [bug 1821980](https://bugzilla.mozilla.org/1821980).
+
+- `mpadded`: Tests for some
+   [mpadded](https://www.w3.org/TR/MathML3/chapter3.html#presm.mpadded)
+   features, which are not in the initial version of MathML Core.
+
+- `menclose`: Tests for the
+   [menclose](https://www.w3.org/TR/MathML3/chapter3.html#presm.menclose)
+   element, which is not in the initial version of MathML Core.
+   See [issue 216](https://github.com/w3c/mathml/issues/216).
+
+- `mo-accent`: Tests for the
+   [mo@accent attribute](https://www.w3.org/TR/MathML3/chapter3.html#presm.mo.dict.attrs),
+   and the corresponding accent property from the dictionary,
+   which are removed from MathML Core.
+   See [bug 1790548](https://bugzilla.mozilla.org/1790548)
+   and [bug 1636428](https://bugzilla.mozilla.org/1636428).
+
+- `negative-lengths`: Tests for negative lengths, for which support or
+   interpretation is unclear in current version of MathML Core.
+   See [issue 132](https://github.com/w3c/mathml-core/issues/132).
+
+- `tables`: Tests for
+   [table features](https://www.w3.org/TR/MathML3/chapter3.html#presm.tabmat)
+   that are in the initial version of MathML Core.
+   See [issue 125](https://github.com/w3c/mathml-core/issues/125).
+
+- `whitespace-trimming`: Tests for
+   [whitespace trimming in token elements](https://www.w3.org/TR/MathML3/chapter2.html#fund.collapse)
+   which is not described in the initial version of MathML Core.
+   See [issue 149](https://github.com/w3c/mathml-core/issues/149).