[css-color-5] "CIE LCH" is ambiguous

While reading the CSS Color 5 spec, the term "CIE LCH" was ambiguous. This could mean CIE LCHuv based on CIE Luv, or CIE LCHab based on CIE Lab.

After digging a bit, it became understandable that what was meant is CIE LCHab.
Please clarify this in the documentation.

CIE LCH is defined in CSS Color 4, not 5 (Color 5 adds relative color syntax to the existing definition). From 9.1. CIE Lab and LCH:

CIE LCH has the same L axis as Lab, but uses polar coordinates C (chroma) and H (hue), making it a polar, cylindrical coordinate system. C is the geometric distance from the L axis and H is the angle from the positive a axis, towards the positive b axis.

There is no ambiguity in this definition.

Thank you

[css-color-5] Add backlinks from relative colors to the corresponding…

@mm2t

@mm2t

After digging a bit, it became understandable

You should not have to dig. I have added links from each relative color form to the absolute form, which is where all the explanation lives. CSS Color 5 just modifies the existing syntax to add relative colors, but readers should be able to find the relevant information easily.

👍 This is indeed nice; especially that specs are often read in a hunt-and-peck fashion.

[css-color-5] Add backlinks from relative colors to the corresponding…

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[css-color-5] "CIE LCH" is ambiguous #13286

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[css-color-5] "CIE LCH" is ambiguous #13286

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svgeesus commented on Jan 6, 2026

mm2t commented on Jan 6, 2026

svgeesus commented on Jan 7, 2026

mm2t commented on Jan 8, 2026

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