By default the DateTime picker will work with IS8601 formatted strings only, but that is far from user friendly. To address this, the picker works with a number of different libraries:

On start up, DateTime will automatically attempt to determine which library is available on your page (if any). If you have multiple libraries and which to choose a specific one, use the static DateTime.use() method - e.g.:

DateTime.use( moment );

The formatting and parsing available to DateTime is entirely dependent upon these libraries and the format option is passed directly to them. Please refer to their relevant documentation for the options each presents.