Turns revisions on or off.
When revisions are turned on, AutoCAD Mechanical toolset tracks the date of the block of xrefs inserted in the drawing. If AutoCAD Mechanical toolset detects a change in an xref, it prompts you for confirmation and adds a revision line to the revisions list. If no revisions list exists, it creates one and prompts you to place it in the drawing area.
Generally, activate this command after changing your drawing. The first time you launch the command, in inserts a block with a header into the drawing.