Although the title of this posting conjures up images of doodling on Heidi Klum or Fabio with a Flair pen, that's not it. :-) Senior DWF Product Manager, Hilde Sevens, taught an Autodesk University 2006 class entitled "Share 3D Autodesk Inventor Designs, Animations, and Assembly Instructions with Your Extended Team." In her class, Hilde shared some tips related to marking up a 3D mechanical model as part of an electronic review process.
You can keep team members up-to-date with design review status and changes throughout the design review process.
When creating a markup on a 3D model, selecting the Callout Tool will generate a new snapshot of the model (you can markup the snapshot).
Create a Markup on the new sheet by using the Callout Tool and selecting the custom Callout.
Update the markup Status by selecting the markup in the Markup Palette and Changing to ‘for review’ in the Properties Palette. You can also add a comment in the notes field to clarify to your customer why you are requesting the change.
Notice how the markup color changes when you change its status. This helps the user of the DWF get immediate feedback as to which Markups are For Review, a Question or Done.
Also of note, when creating the markup you can hold Shift to constrain the markup.