How to implement Schema.org on HTTPS pages?

Question

Is it correct to statically set up Microdata’s itemtype attribute with HTTP value (http://schema.org/WebPage) on HTTPS pages or do I need to use HTTPS value (https://schema.org/WebPage) on all pages?

Since both HTTP and HTTPS versions of the site are available, can I set it up to //schema.org/WebPage or not?

Answer 1

There's been an update to that answer on Webmasters SE (dated November 2015), with a link to the schema.org FAQ about https:

Q: Should we write https://schema.org or http://schema.org in our markup?

The short of it is that schema.org will be moving to https, and you can use https URLs now, but there's no rush to switch.