dellus wrote
Is it an AutoCAD convention that Layer 0 is the construction layer?
No, layers named 0, 1, 2, etc. are conventionally for objects. This drafting guide for manual drafting and AutoCAD provides a good overview of all the conventional layers and line types for CAD drawings:
http://www.thecadacademy.com/instructorportal/Fundamentals_of_Drafting_Sample.pdf#page=14