This information was on a sheet insert inside the 2001 cookbook/manual that came with the sets from 2001 on.
CAUTION: READ AND FOLLOW THE INSTRUCTIONS BELOW. FAILURE TO DO SO MAY CAUSE DAMAGE TO YOUR COOKWARE, STOVE OR CREATE A POTENTIAL SAFETY HAZARD.
1. DO NOT EXPOSE PRODUCT TO HEAT SOURCE WITHOUT FOOD INSIDE. PREHEATING IS NOT NECESSARY AND MAY CAUSE DAMAGE TO YOUR COOKWARE.
2. THIS PRODUCT IS INTENDED FOR USE ON LOW OR MEDIUM HEAT SETTINGS ONLY. OVERHEATING CAN CAUSE FOODS TO BURN AND DISCOLOR THE COOKWARE.
3. NEVER USE A HEAT SOURCE LARGER THAN THE BASE OF THE COOKWARE. DO NOT ALLOW FLAME OR HEAT SOURCE TO EXTEND BEYOND THE SIDES OF THE COOKWARE. DO NOT ALLOW THE HANDLES OF YOUR COOKWARE TO EXTEND OVER ANOTHER BURNER OR OVER THE EDGE OF THE STOVE
4. ALWAYS USE THE HANDLES WHEN REMOVING THE COOKWARE FROM THE STOVE, DO NOT TOUCH THE SIDES, BASE, OR LID OF THE COOKWARE AS IT REMAINS VERY HOT EVEN AFTER BURNER HAS BEEN TURNED OFF. ALWAYS USE POTHOLDERS WHEN HANDLING THE COOKWARE.
5. DO NOT ALLOW THE CONTENTS OF COOKWARE TO BOIL DRY. DOING SO MAY DAMAGE YOUR COOKWARE OR CREATE A POTENTIAL SAFETY HAZARD.
6. DO NOT USE THIS COOKWARE ON A GLASS FLAT TOP COOKING SURFACES.