HTML Guide
The projection media type was deprecated in Media Queries 4.
Media types describe the general category of a device, for example screen, print and speech.
CSS 2.1 and Media Queries 3 defined several additional media types (tty, tv, projection, handheld, braille, embossed, and aural), but they were deprecated in Media Queries 4 and shouldn’t be used.
Related W3C validator issues
The deprecated property longdesc on img elements was used in HTML4 to specify the URL of a text or HTML file which contained a long-form description of the image. This could be used to provide optional added details beyond the short description provided in the title or alt attributes.
Here’s an example from HTML4:
<img
src="cat.jpg"
alt="Smiling Cat"
longdesc="image-descriptions/smiling-cat.html" />This, however, is no longer valid in HTML5 and can be converted to the following instead:
<a href="image-descriptions/smiling-cat.html">
<img src="cat.jpg" alt="Smiling Cat" />
</a>