Code: [http://dxr.mozilla.org/mozilla-central/source/layout/base/nsCSSFrameConstructor.h layout/base/nsCSSFrameConstructor.h] and [http://dxr.mozilla.org/mozilla-central/source/layout/base/nsCSSFrameConstructor.cpp layout/base/nsCSSFrameConstructor.cpp]
==== Physical Sizes vs. Logical Sizes ====
TODO: Discuss inline-size (typically width) and block size (typically height), writing modes, and the various logical vs. physical size/rect types.
==== Reflow ====