CITguy
commented
5 years ago Doctype Reference
HTML 5 (and beyond)
<!DOCTYPE html>- OK - I've high confidence that the vast majority of pages with this doctype are using CSS instead of stylistic attributes.
XHTML 1.0 Strict
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">- OK - DTD doesn't support stylistic attributes
XHTML 1.0 Transitional
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">- WARN - DTD supports old stylistic attributes
<body>color attributes:text,link,vlink,alink,bgcolor- elements supporting
bgcolorattribute:<table>,<tr>,<th>,<td>
XHTML 1.0 Frameset
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd">- WARN - Same as XHTML 1.0 Transitional
XHTML 1.1
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">- OK - Same as XHTML 1.0 strict
XHTML 1.1 Basic
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.1//EN" "http://www.w3.org/TR/xhtml-basic/xhtml-basic11.dtd">- OK - Same as XHTML 1.0 Strict
HTML 4.01 Strict
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">- OK - DTD doesn't support stylistic attributes
HTML 4.01 Transitional
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">- WARN - DTD supports stylistic attributes
<body>color attributes:text,link,vlink,alink, andbgcolor(%bodycolorsDTD entity)bgcolorattribute:<table>,<tr>,<th>,<td>
HTML 4.01 Frameset
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd">- WARN - Identical to HTML 4.01 Transitional
Conclusion
OK
- XHTML 1.0 Strict
- XHTML 1.1 (any)
- HTML 4.01 Strict
- HTML 5
WARN
- XHTML 1.0 Transitional and Frameset
- HTML 4.01 Transitional and Frameset
- SVG
- MathML
UNSUPPORTED
- HTML 3 (or older)
Specifically, it doesn't apply correctly to documents with a declared doctype that doesn't support CSS (e.g., HTML 3).
For example: We can't reliably apply
filter: grayscale(100%);if the document relies ontext,bgcolor, or similar stylistic attributes used in HTML 3 or older.Maybe provide a warning when toggling that the doctype is too old to reliably function.