Appears when you choose Save As.
The Save File As dialog has standard Windows file save controls. At the right, the Thumbnail area shows a preview of the scene whose file name is highlighted in the list on the left.
Tip: You can resize the dialog by dragging an edge or a corner.
Clicking the plus button appends a sequence number to the file name you entered, or increments the sequence number if the name already has one, and then saves the file to that name.
For example, if you have highlighted a file named test00.max, clicking the plus button changes the name to test01.max and then saves test01.max.