The extensions that are not autoladed, plus the macros they define are

• action: \mathtip, \texttip, \toggle

• begingroup: \begingroup, \endgroup, \gdef, \global

• cancel: \cancel, \bcancel, \xcancel, \cancelto

• color: \color, colorbox, fcolorbox, \DefineColor

• enclose: \enclose,

• extpfeil: \Newextarrow, \xlongequal, \xmapsto, \xtofrom, \xtwoheadleftarrow, \xtwoheadrightarrow

• mhchem: \ce, \cee, \cf

There are also a bunch of macros in the AMSmath and AMSsymbols extensions that aren't autoloaded, but the configuration used here already includes those, so I don't list them here.

Some of these are non-standard (e.g., the action and enclose extensions, which give you access to the underlying MathML elements). These are documented in the TeX support documentation.

I expect that SO and SE will eventually include the begingroup extension so that they can isolate definitions to the question/answer/comment that defines them (it was because of that need that I added the begingroup extension in the first place). So that doesn't leave too many that aren't available.

Finally, there is a new extension, autoload-all, that will pre-define all the macros that are defined in any extension to autoload that extension, so if SO and SE include that extension, it will make all the macros available in one step (without having to load all the extension files, as they will be loaded only when they are actually needed). That extension was added in response to this discussion.

Hope that helps.

The extensions that are not autoloaded, plus the macros they define are

• action: \mathtip, \texttip, \toggle

• begingroup: \begingroup, \endgroup, \gdef, \global

• cancel: \cancel, \bcancel, \xcancel, \cancelto

• color: \color, colorbox, fcolorbox, \DefineColor

• enclose: \enclose,

• extpfeil: \Newextarrow, \xlongequal, \xmapsto, \xtofrom, \xtwoheadleftarrow, \xtwoheadrightarrow

• mhchem: \ce, \cee, \cf

There are also a bunch of macros in the AMSmath and AMSsymbols extensions that aren't autoloaded, but the configuration used here already includes those, so I don't list them here.

Some of these are non-standard (e.g., the action and enclose extensions, which give you access to the underlying MathML elements). These are documented in the TeX support documentation.

I expect that SO and SE will eventually include the begingroup extension so that they can isolate definitions to the question/answer/comment that defines them (it was because of that need that I added the begingroup extension in the first place). So that doesn't leave too many that aren't available.

Finally, there is a new extension, autoload-all, that will pre-define all the macros that are defined in any extension to autoload that extension, so if SO and SE include that extension, it will make all the macros available in one step (without having to load all the extension files, as they will be loaded only when they are actually needed). That extension was added in response to this discussion.

Hope that helps.