Good question. I haven’t found anything in the documentation either. Based on setting the value and changing a password, I have the generated the following table.
0 = no complexity requirements as you can use digits, lower and upper case letters, symbols
1 = no complexity requirement, same as zero. I do suspect that you have to have a non-empty password.
2 = Error "it must contain characters from at least 2 categories(digits, lower and upper case letters, symbols)
3 = Error "it must contain characters from at least 3 categories(digits, lower and upper case letters, symbols)
4 = Error "it must contain characters from at least 4 categories(digits, lower and upper case letters, symbols)
I did not test for no characters as this should be forced by the min length setting.