Google Data API: what is the limit of Extended Properties?

Is there any limit on number of properties and value length in Extended Properties of Google Data 开发者_开发技巧API (in particular Calendar API)?

You can add extended properties (arbitrary name-value pairs) to Calendar events. These can be used to store application-specific IDs or other small amounts of information your application needs when interacting with a Google Calendar. The name of a property can contain up to 47 characters, and the value can contain up to 1024 characters. Extended properties are only accessible through the API – they do not appear in the Calendar user interface.