The content of an HTML element will be parsed in inline mode unless the opening tag is followed by two linebreaks, in which case it is parsed in block mode. (Inline mode means that block mode formatting such as tables, lists and headings is not recognised).
Attributes in HTML tags can be specified as a literal, a transclusion or a macro invocation. For example, here the value of the `href` attribute will be set to the value of the tiddler MyLinkDestination:
Note that the link should be set a value of the `rel` attribute is had `noreferrer` to maintain the secrecy of URLs of private TiddlyWiki's (eg on Dropbox).