Which two steps must be completed to extend an OOTB AccountType typelist that does not have any extension files?

To extend an out-of-the-box (OOTB) AccountType typelist that does not have any extension files, creating the AccountType.ttx file is essential. This file serves as a custom extension for the typelist, allowing you to include additional values or modify its characteristics. Without this TTX file, there would be no mechanism to add custom entries or modifications to the existing typelist, which is the primary purpose of an extension in Guidewire.

Understanding the rest of the steps provides context for why they may not be necessary or applicable in this scenario. While verifying that the typelist's final property is set to true might be relevant in certain contexts, the requirement to extend would not depend on this attribute if no extension files exist. Setting a default value for the AccountType in the database could be relevant in other contexts but does not directly relate to extending a typelist. Lastly, ensuring that the AccountType is public pertains to visibility and access but does not directly impact the ability to extend the typelist itself.

Thus, the creation of the AccountType.ttx file is the critical first step required for the extension process.