If a recipe were to call for you to cook for 1:00 minute at 100% power, then you would use the Power 10 level. Therefore, a recipes calling for other power levels would be:
1 = 10%
2 = 20%
3 = 30%
4 = 40%
5 = 50%
6 = 60%
7 = 70%
8 = 80%
9 = 90%
I don't think you would use the 0.
The only time you would need to use a conversion chart, is if the recipe were written for a different wattage oven. For example, if the recipe was written for 850-Watt oven and called to cook for 1:00 minute at 50%, then you would need to use one of the
850-Watt Oven to 700-Watt Oven Conversion Chart to find out that you need to cook 1 minute 13 seconds, but you would still cook at 50% power to achieve the correct results from the recipe in your 700-Watt oven.
Microwaves cook very quickly, and while most recipes call for cooking at 100% power, there are times you need to slow down the cooking process; hence the power levels.