I think that you are asking if the Document Manager has a function that Locks the document when it is checked out, similar to when a project is locked when it is opened in MSP, If that is the case, then the answer is yes, that is the standard functionality. When you check out a document, the document is locked in the Document Manager. if you go back to the Document Manager and look at that document while it is checked out, you will see a check mark on the document indicating that status, and the check out action is not available. Although you can still open the document while it is checked out, you cannot save edits back to the document without being the person who checked it out and formally checking it back in.