Google has updated its rel canonical documentation and makes it more clear how Google manages rel canonical annotations.
With this update, Google aims to explain the process of canonical annotation. This update does not mean changes in Google's rel=canonical annotations handling process.
The documentation refers to RFC 5988 as the standard Google follows for the link relation canonical. The RFC defines specifications for HTML rel link attributes.
Usually, Canonical tags are used to identify the original page of your website if there are any other duplicate pages.
The recent changes to the documentation include adding the word "explicit" to clarify that Google supports explicit rel canonical link annotations as described in RFC 6596.
Additionally, a new paragraph emphasizes that rel=canonical annotations with certain attributes are not used for canonicalization and recommends using appropriate link annotations for specifying alternate versions of a page.
Despite these updates, Google's usage of canonical and alternate link elements remains unchanged.