To mark a file or document as Reserved, just use the Actions menu to Mark as Reserved. This won't lock the document, but it will alert other users you are planning to update the item and they should wait or contact you before editing.
Reserving a document or file is a lightweight way to alert other users you're working on a document. The Reserved badge doesn't prevent anyone else from editing, but it shows information about who is working with the item, making it easy for other people to check in with you before adding their own edits. This is especially useful if you're using uploaded files, but can't use the Jive for Office program for collaborative editing.
To mark and unmark a file as Reserved:
To mark a file or document, go to its page and in the Actions menu, click
Mark as Reserved.
You'll see the Reserved badge at the top left of the file preview
display area (for uploaded files) or at the top of the document, with a time
stamp indicating who marked it, and when.
To unmark the file, use any of the following methods:
Click the Unmark link at the top
Publish the item. When you or anyone else publishes a new version, the
Reserved badge is removed.
Mark it as Final, Official or Outdated. These markings override Reserved and the reserved badge is removed.