The documentation portal is undergoing maintenance. During this period, you can't create any new user credentials. If you do, you'll need to recreate the user credential after the maintenance period ends.
If you use XML API and do not specify an encoding type, Address Verification sets the encoding to UTF-8 or UTF-16 based on whether you use 8-bit or 16-bit API functions. For direct API, the default is ISO-8859-1.