Not sure if this is in the right place... however.
For a sighted user, a visually prominent 'call to action' hyperlink in a document is normally created following the principle of Fitts' law (ie: targets that are larger and closer to the pointing device are easier to hit than ones that are smaller and further away).
Large, colourful with enticing text, it's pretty clear to a sighted user what the primary call to action on a page would be.
There is no equivalent of a call to action link for a screen reader user, as all links are given equal weighting in a rotor (VoiceOver) or list view (JAWS / NVDA).
In usability studies with screenreader users I've observed in documents with multiple links it can be difficult for users to determine what the primary or secondary call to action is (there's a similar thread on a webaim mailing list).
In the interests of providing an equivalent user experience, perhaps adding an attribute to the native
<a> might work, or maybe use of WAI-ARIA could plug a semantic gap where HTML cannot facilitate.
I'd like to propose a semantic role could be applied to a hyperlink to programmatically determine if it is the primary or secondary call to action in document.
Maybe a little bit like this.
<a href="tickets.html" role="calltoaction" aria-level="1">Buy tickets</a>
<a href="contact.html" role="calltoaction" aria-level="2">Contact</a>