These are memoranda which have been issued by USCIS (and INS prior to the creation of USCIS) on this topic. You will need the free Adobe Reader software to view these files.
Supplemental Guidance Relating to Processing Forms I-140 Employment-Based Immigrant Petitions and I-129 H-1B Petitions, and Form I-485, Adjustment Applications Affected by the American Competitiveness in the Twenty-First Century Act of 2000 (...) (138KB PDF)Donald Neufeld, Acting Associate Director, Domestic Operations05/30/2008
Interim Guidance for Processing I-140 Employment-Based Immigrant Petitions and I-485 and H-1B Petitions Affected by the American Competetiveness in the Twenty-First Century Act of 2000 (AC21) (Public Law 106-313) ( PDF)Michael Aytes HQOPS Docket # USCIS-2008-006712/27/2005
Interim Guidance for Processing Form I-140 Employment-Based Immigrant Petitions and Form I-485 and H-1B Petitions Affected by the AC21 Act ( PDF)William R. Yates HQOPS05/12/2005