From Autodesk Services & Support:
You want information about FLEXnet® feature codes for Autodesk 2011 products.
When you start the network version of an Autodesk product, a request is made to the network for a license. The Network License Manager controls the licenses that are issued and handles license requests through feature codes. Feature codes are specific to the networked application. Any network version of an Autodesk product has a specific FLEXnet® feature code.
Feature codes are necessary because the Network License Manager is designed to administer licenses for multiple Autodesk applications. An example of feature code usage in a log file entry is shown below.
Sample log file entry:
11:00:04 (adskflex) OUT: "40100ARCHDESK_3_3F" user@hostname
Click here for the complete list of feature codes for Autodesk 2011 applications from Autodesk Services & Support.