I have started to understand auto enter and validation field options.

I want to ensure that a field isn't empty AND contains an approved value.

For instance:

• The field should not be empty (“”, NULL, FALSE, 0, or Empty).
• The field should contain either the value "Cat" or "Dog".

What are some of the best ways to accomplish this? Should I use value lists or a calculation to validate the field? What about using a script? What is the best sentinel?

The state field must contain a two letter state abbreviation.