Which application type must disclose its subject matter in the parent application?

The requirement for a divisional application is that it must disclose subject matter that was originally presented in the parent application. This is because a divisional application is filed to separate out claims that were deemed patentably distinct from those in the parent application, typically due to a restriction requirement. By ensuring that the claimed inventions in the divisional are drawn from the parent application, it maintains a clear lineage of the disclosure and the claims' validity.

In contrast, a continuation application allows for different claims based on the same disclosure, while a continuation-in-part application may introduce new subject matter not present in the parent. A provisional application serves as a placeholder and does not require claims or formal disclosures. Understanding these distinctions is crucial for determining the appropriate application type when seeking patent protection.