1. CSS revert value

    A CSS keyword value that resets a property's value to the default specified by the browser in its UA stylesheet, as if the webpage had not included any CSS. For example, `display:revert` on a `<div>` would result in `display:block`. This is in contrast to the `initial` value, which is simply defined on a per-property basis, and for `display` would be `inline`.

  2. CSS3 Cursors (original values)

    CSS3 cursor values added in the 2004 spec, including none, context-menu, cell, vertical-text, alias, copy, no-drop, not-allowed, nesw-resize, nwse-resize, col-resize, row-resize and all-scroll.

  3. CSS currentColor value

    A CSS value that will apply the existing `color` value to other properties like `background-color`, etc.

  4. Datalist element

    Method of setting a list of options for a user to select in a text field, while leaving the ability to enter a custom value.

  5. Resource Hints: preload

    Using `<link rel="preload">`, browsers can be informed to prefetch resources without having to execute them, allowing fine-grained control over when and how resources are loaded. Only the following `as` values are supported: fetch, image, font, script, style, track.

  6. Web Storage - name/value pairs

    Method of storing data locally like cookies, but for larger amounts of data (sessionStorage and localStorage, used to fall under HTML5).

  7. relList (DOMTokenList)

    Method of easily manipulating rel attribute values on elements, using the DOMTokenList object (similar to classList).

  8. audioparam api: linearramptovalueattime

  9. domtokenlist api: replace: boolean return value (not void anymore)

  10. domtokenlist api: value

  11. domtokenlist api: values

  12. gpuadapter api: requestdevice: request unknown limits with `undefined` value

  13. gpudevice api: createpipelinelayout: `bindgrouplayouts` array accepts `null` values.

  14. highlightregistry api: values

  15. highlight api: values

  16. htmlimageelement api: sizes: `auto` value

  17. htmlinputelement api: value

  18. htmlinputelement api: valueasdate

  19. htmlinputelement api: valueasnumber

  20. htmllielement api: value

  21. nodelist api: values

  22. presentationavailability api: value

  23. radionodelist api: value

  24. validitystate api: valuemissing

  25. css property: -moz-orient: `inline` value

  26. css property: align-items: supported in flex layout: `end` value supported in flex layout

  27. css property: align-items: supported in flex layout: `start` value supported in flex layout

  28. css property: align-self: supported in flex layout: `stretch` value supported in flex layout

  29. css property: background: values of `background-clip` longhand

  30. css property: color-interpolation: `lineargradient` value

  31. css property: color-interpolation: `linearrgb` value

  32. css property: dynamic-range-limit: `<dynamic-range-limit-mix()>` values

  33. css property: text-underline-offset: percentage values

  34. types: `<color>`: `light-dark()`: `<image>` values

  35. types: `<timeline-range-name>`: `scroll` value

  36. html element: li: value

  37. headers http header: content-security-policy: `report-sample` source value

  38. headers http header: content-security-policy: `strict-dynamic` source value

  39. headers http header: content-security-policy: `unsafe-hashes` source value

  40. elements: mfrac: linethickness: nonzero unitless values (e.g. 5 to mean 500% the default thickness)

  41. elements: mfrac: linethickness: `thin`, `medium`, `thick` values

  42. svg element: ellipse: fill: `context-fill` value

  43. svg element: fecomposite: operator: `lighter` value

  44. svg element: polyline: fill: `context-fill` value