indicates that the document is checked out to you.As documents are checked in and out, icons appear to the left of the document name indicating the check in/out state as follows:
indicates that the document is checked out to you.
indicates that the document is locked and checked out to another author.
No icon indicates that the document is checked in and available to any author.
These icons appear in various places such as the Library and Outline Editor as well as on document editor tabs and various views. Also note that additional columns in the Details view of the Library and Outline Editor display the check in/out state and version number. The Checked Out By column displays the name of the author who is currently using the document.