Direction of slant for italic/oblique RTL text

RTL African scripts include N'Ko, Adlam, & Ajami.

This issue asks questions about the requirements for oblique text in these scripts, and provides preliminary text for a gap-analysis topic. (There is a similar issue for Standard Arabic/Persian at https://github.com/w3c/alreq/issues/93.)

Questions

RTL italicised text for Arabic and Hebrew can be found leaning to the left, rather than to the right as in English.

[Q1] In what direction should African RTL text lean when oblique?

The Jamra-Patel site has a couple of nice examples of italicised text. First, N'Ko, where text leans to the left:

The example of italicised Adlam text, however, leans to the right:

[Q2] Should embedded Latin (or other LTR) text lean to the left or right, when the surrounding text leans to the left?

Here's an example in Standard Arabic:

Support on the Web

Unless a font comes with an italic or oblique face, slanted text on the Web will be produced synthetically by the browser skewing the text. I think i'm safe in saying that no mechanism is currently specified in any browser for left-leaning skews, but provision for it is made in the CSS Fonts Level 4 draft.

I'm not aware of any tests for this behaviour, but i may write some, if time allows.

Prioritisation of this gap

Third question:

[Q3] Is slanted/oblique/italicised text a common feature of these scripts. Do users expect to have it and use it regularly, or is it perhaps an artefact of Western-based digitalization whose need is not felt by users of these scripts?

What colour would we use to describe this situation in the Language Matrix?

Begin with the questions in the issue and the CSS Fonts Level 4 font-style reference; compare the N'Ko and Adlam examples and the embedded Latin case. Done means recording agreed direction for slanting, whether oblique text is commonly expected in these scripts, and the appropriate Language Matrix color; add tests only if the proposed behavior requires them.