You use Autodesk Design Review to insert markups into a DWF file. A markup is a single comment or a redline geometry correction inserted into a DWF file.
Using Autodesk Design Review, you can add markups electronically, just as you would mark up a paper version of the drawing. In addition to the redline geometry you add to the DWF file, you can also assign a status to the markup and add comments. The markups and their status are saved in the DWF file. For more information about creating markups in Autodesk Design Review, see the Autodesk Design Review Help documentation.