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The alignment properties are divided into two dimensions, one for each flow-relative dimension. In order to have terms for all four sides of a box, the terminology used in each dimension is different: the inline dimension uses start/end, while the stacking dimension uses before/after. (But see open issue on renaming before/after.) Right now the layout specs proposing new alignment properties use start/end keywords in both dimensions.
Note: Flexbox will be the first spec to go to CR with logical keywords.
Should alignment properties use flow-relative terms, or use start/end in both dimensions?
The proposal is to have the Box Alignment proposal's '-align' properties, which align in the stacking dimension, to use block-relative directions, not start/end (which are the inline-relative terms).