Logical shorthand notes & side quests

Why inline-size but padding-inline? ¶

This is a question from @johanwestling on Mastodon:

But why the opposite property naming order? I mean padding, padding-block, padding-inline for example.

I wasn’t in the CSS Working Group when this decision was made, but here’s what I’ve found so far.

• December 2010 Writing Modes spec defines terms length (logical height) and measure (logical width) https://www.w3.org/TR/2010/WD-css3-writing-modes-20101202/#dimensions
• March 2014 Writing-Modes spec uses extent (block) & measure (inline): https://www.w3.org/TR/2014/CR-css-writing-modes-3-20140320/#abstract-dimensions
• March 2014 CSSWG resolves to use inline-(something) and block-(something) instead: https://lists.w3.org/Archives/Public/www-style/2014Mar/0255.html
• March 2014 The discussion is mostly about what (something) should be, and agreeing that a hyphen makes block-size more clear than block size (the 2D size of a block?): https://lists.w3.org/Archives/Public/www-style/2014Mar/0479.html
• July 2014 first commit to Logical Properties spec includes length and measure as the property names: https://github.com/w3c/csswg-drafts/blob/156b081188738ea7ecd1aa6a168e4347d339b19f/css-logical-props/Overview.bs
• October 2014 the properties are updated to inline-size and block-size: https://github.com/w3c/csswg-drafts/commit/0a24110043cb3f3033fb22661297046a54465eda
• December 2015 Writing Modes spec uses inline-size and block-size: https://www.w3.org/TR/2015/CR-css-writing-modes-3-20151215/#abstract-axes
• May 2017 First Public Working Draft of Logical Properties: https://www.w3.org/TR/2017/WD-css-logical-1-20170518/

Github issues only go back to late 2015, after the names seem to be settled, so I can’t find any discussion there.

Many of the people participating in those conversations are still involved with the CSSWG today, so I can ask around for more information – but it seems to me that the likely answer is:

• The logical margin, padding, and border properties were added as longhand versions of existing properties, with the well established <base-property>-<sub-property> syntax.
• At the time, width and height were not longhand properties with a shared shorthand base-property, and so the logical alternatives were not designed as longhand sub-properties.
• inline-size and block-size already existed as conceptual terms, and they read better than the flipped size-inline and size-block. Without a shorthand property to base the names off, there’s little reason to change them.
• Now that we are adding a size shorthand, the pattern seems inconsistent – but it wasn’t even a consideration previously.