Layer 0 was usually the default layer. In this file, it was locked and red. He hovered his mouse over the lock icon in the layer properties manager. He clicked it. A dialog box popped up:
This release focused on streamlining user interaction and expanding 3D capabilities. Major updates included: autocad 2012 portable
The portable version of AutoCAD 2012 offers many of the same features as the installed version, including: Layer 0 was usually the default layer