Why two different credentials: CustomerCode and UserCode?
Individuals have their own UserCode and Password.
Corporate Subscriptions have a separate CustomerCode and Password.
UserCodes allow Individuals to login to CheckTLS and interact with it. CustomerCodes allow unattended use of Web Services.
Having separate credential types allows Individuals to keep their credentials secret and not listed in the source code for Web Service calls.
Corporate Subscribers can see their CustomerCode and CustomerPass HERE.