The API supports two methods for continuing action=query when more results are available, the simple method[1] and the raw method.[2] The raw method is currently the default for historical reasons, but as the simple method is much easier for new users to use *correctly* that really should be the default.
To make this transition easy for clients, the current plan is to make the change on the following timetable:
* Starting with 1.24wmf22,[3][4] action=query will recognize a "rawcontinue" boolean input parameter. Clients that wish to continue using the raw method for continuation should begin supplying this parameter with all action=query queries.