Boundary Conditions

Here for reference is a complete listing of the rel and type attributes I have observed for link elements in Google Calendar feeds. These are a superset of the attributes contained in link elements found in event feeds. Google Calendar feeds do not use all available combinations of permitted Atom link elements. A complete list of Atom link relations is here. Atom requires that each element have a maximum of one link of each relation and type. Types are specified here for Atom elements. None of the observed relations from outside the Atom namespace have types.

link rel='alternate' type='application/atom+xml'
link rel='alternate' type='text/calendar'
link rel='alternate' type='text/html'
link rel='edit' type='application/atom+xml'
link rel='http://schemas.google.com/acl/2007#accessControlList'
link rel='http://schemas.google.com/g/2005#batch'
link rel='http://schemas.google.com/acl/2007#controlledObject'
link rel='http://schemas.google.com/g/2005#feed'
link rel='http://schemas.google.com/g/2005#post'
link rel='next' type='application/atom+xml'
link rel='previous' type='application/atom+xml'
link rel='self' type='application/atom+xml'

Notes

Alternate links point to an alternate representation of the same resource. There are three types represented in Google Calendar feeds; the type specifies that nature of the alternate representation. The application/atom+xml type alternate links are all contained inside elements and point to the individual entry. The text/html type links are to html representations of the calendar or event. The text/calendar are links to ics format calendar files.

The edit links are used to update or delete calendars or events. The post links are used to create calendars or events. The edit links are defined in the Atom Publishing Protocol. Post links are Google’s own invention.

Batch links identify the uri for posting batch request. I have no experience with batch requests, but according to the documentation insert, update, delete, or query operations are permitted.

Feed links in all observed cases are exactly the same as the id of the feed. The self links are related to the feed links and id, but also contain the (possibly implicit) url parameters that were used to retrieve the feed.

AccessControlList links identify the location of the access control list (acl) for the feed. ControlledObject links identify the feed that the acl pertains to.

Next and previous specify Atom Publishing Protocol partial collections. Next and previous are paged feeds.