1. :indeterminate CSS pseudo-class

    The `:indeterminate` pseudo-class matches indeterminate checkboxes, indeterminate `<progress>` bars, and radio buttons with no checked button in their radio button group.

  2. indeterminate checkbox

    Indeterminate checkboxes are displayed in a state which is distinct both from being checked or being unchecked. They are commonly used in hierarchical checkboxes to indicate that only some of the checkbox's descendants are checked.

  3. htmlinputelement api: indeterminate

  4. css selector: `:indeterminate`: applies to `<input type="checkbox">` elements

  5. css selector: `:indeterminate`: applies to `<progress>` elements

  6. css selector: `:indeterminate`: applies to `<input type="radio">` elements