On the standards track: Yes
Is Experimental: No
Is Deprecated: No
In Chrome version 117 on 2023-09-12 Note: If the font does not have subscript glyphs, then substitute characters are not synthesized (see bug 352218916).
In Chrome Android version 117 on 2023-09-12 Note: If the font does not have subscript glyphs, then substitute characters are not synthesized (see bug 352218916).
In Edge version 117 on 2023-09-15 Note: If the font does not have subscript glyphs, then substitute characters are not synthesized (see bug 352218916).
In Firefox version 34 on 2014-12-01
In Firefox for Android version 34 on 2014-12-01
Not in Internet Explorer
Not in Quest Browser
In Opera version 103 on 2023-10-03 Note: If the font does not have subscript glyphs, then substitute characters are not synthesized (see bug 352218916).
In Opera Android version 78 on 2023-10-23 Note: If the font does not have subscript glyphs, then substitute characters are not synthesized (see bug 352218916).
In Safari version 9.1 on 2016-03-21 Note: If the font does not have subscript glyphs, then substitute characters are not synthesized (see bug 151471).
In Safari on iOS version 9.3 on 2016-03-21 Note: If the font does not have subscript glyphs, then substitute characters are not synthesized (see bug 151471).
In Samsung Internet version 24.0 on 2024-01-25 Note: If the font does not have subscript glyphs, then substitute characters are not synthesized (see bug 352218916).
In WebView Android version 117 on 2023-09-12 Note: If the font does not have subscript glyphs, then substitute characters are not synthesized (see bug 352218916).
In WebView on iOS version 9.3 on 2016-03-21 Note: If the font does not have subscript glyphs, then substitute characters are not synthesized (see bug 151471).