We're exploring text/html paste behaviours in Mozilla bug 586587  and running into some tricky questions I'd like to discuss here.
Basically, on Windows IE and other apps that write HTML to the clipboard use the CF_HTML format. This format is simply described as > headers (name:value meta data) > > <html><head></head> > <body> > <!--StartFragment-->HTML<!--EndFragment--> > </body> > </html> where the StartFragment / EndFragment comment tags are inserted by implementations writing HTML to the clipboard to show where the actually selected content starts and ends. Several very common implementations (including I believe Microsoft Word's) will add tags like STYLE outside of the StartFragment/EndFragment tags and add rules that may be significant for rendering the content of the fragment correctly. Also noteworthy is that the meta data may include a SourceURL property showing the URL of the page you copied from. So, because of the significance of the STYLE information and other stuff outside Start/EndFragment, certain browsers return the full document including the Start/EndFragment comment tags when a script does getData('text/html'). This is obviously very useful when there's important stuff outside these tags. It still means scripts have to do extra work to find those comments and extract the content inside them to know what data a user actually intended to paste. This also adds a risk that scripts will be tested only on Windows and authored to require those comments and fail if they aren't there on other platforms. Should we, then, standardise returning the full document including Start/EndFragment comments (basically requiring or encouraging other platform implementations to start using those comments when serializing HTML for the OS clipboard) - or should getData() return only what's inside the Start/EndFragment tags? Are any other important platforms already using CF_HTML conventions, or would their developers balk at being encouraged to do so? On a related topic, I see SourceURL as useful (could be used to properly attribute citations automatically and such) - it would be nice to standardise DataTransfer.sourceURL or something like that, to be set when available. -Hallvord (editor of https://w3c.github.io/clipboard-apis/ )  https://bugzilla.mozilla.org/show_bug.cgi?id=586587