Clarify the baseline value during the top-to-bottom writing mode for Latin text

[RazrFalcon]

https://www.w3.org/TR/SVG/text.html#WritingModeProperty
https://www.w3.org/TR/css-writing-modes-3/#vertical-modes

It's probably CSS Writing Modes Level 3 related. I'm not sure. For now, I'm experiencing the problem during the SVG 1.1 rendering, but I'm sure that this can be reproduced in HTML too (I'm not familiar with it).

<svg viewBox="0 0 200 200" xmlns="http://www.w3.org/2000/svg" font-family="Arial" font-size="64">
    <path id="crosshair" d="M 20 100 L 180 100 M 100 20 L 100 180" stroke="gray" stroke-width="0.5"/>
    <text id="text1" x="120" y="30" writing-mode="tb">Text</text>
    <rect id="frame" x="1" y="1" width="198" height="198" fill="none" stroke="black"/>
</svg>

As you can see, the text has a different baseline(?). Which one is the correct one? Is this explained somewhere?

[svgeesus]

Thanks for the nicely illustrated and documented issue!

SVG 2 defers to CSS Writing Modes 3, so please re-raise the issue over there

[fantasai]

Reported #629 which is the SVG spec issue this testcase is raising.