Should `touch-action` support logical directions like `pan-inline` / `pan-block`?

This question was prompted by the Pointer Event issue at https://github.com/w3c/pointerevents/issues/505

What is touch-action?

Imagine you have an element on a webpage (like a map or a list) that you can interact with using touch. The touch-action CSS property tells the browser how to handle finger swipes on that element:

• touch-action: auto; (the default): The browser tries to figure out if you're scrolling or zooming the page.
• touch-action: none; : The browser doesn't handle swipes for scrolling/zooming.

Directions in touch-action

There are some values like pan-left, pan-right, pan-up, and pan-down. These tell the browser: "Only handle swipes for scrolling in this specific direction."

Example: imagine a list that's scrolled all the way to the top. The developer might set touch-action: pan-down; on it. This means:

• If the user swipes down (to scroll down the list), the browser handles the scrolling.
• If the user swipes up (trying to scroll past the top), the browser doesn't scroll.

The Problem: Physical vs. Logical Directions

These pan-left, pan-right, pan-up, pan-down values are based on the physical screen directions.

We are considering adding logical values like:

• pan-inline: Allow scrolling only in the direction text flows (e.g., right for LTR horizontal, left for RTL horizontal).
• pan-block: Allow scrolling only in the direction perpendicular to text flow (e.g., down for horizontal text).
• Maybe also pan-inline-reverse and pan-block-reverse for when content is scrolled to the end.

These logical values would automatically adapt to the element's direction (ltr/rtl) and writing mode (horizontal/vertical).

My question is: is adding these logical values (pan-inline, pan-block, etc.) important for authors working with RTL languages?

Alternatives: authors could achieve the same result without these new values. They could:

1. Write separate CSS rules using direction selectors (like :dir(rtl)). For example:

   .myList:dir(ltr) { touch-action: pan-right; }
   .myList:dir(rtl) { touch-action: pan-left; }
   

2. Set the touch-action property using JavaScript after checking the element's direction.

Start by reading the linked Pointer Events issue at w3c/pointerevents#505 and the discussion in this issue about logical versus physical touch-action directions. The work is complete when the project has a resolved position on whether values such as pan-inline, pan-block, and their reverse forms are needed for RTL and vertical writing modes.