These two commands only have relevance when a document is in a vault. A document that has not been checked out will be opened read only in the CAD application. This means that while the document can be modified, it cannot be saved as the original name. It can be save as a different name. If the user uses the check-out command in the add-in, then the document till be closed and reopened with read-write permissions, assuming that no one else has already checked this document out. Should that be the case, then the user will be given an error message and the check-out will have failed. After the user has saved the document, he can check it in. If the user does not check the document in at that time, it still has read write permissions and other people will not be able to check it out.
