What are the concepts to begin understanding to not ever let a field be empty or not one of you possible values you want?  For instance:

• Cat or Dog for the purpose of what you are doing are all you need to receive as data
• You also never want it to be “”, NULL, FALSE, 0, or Empty (so something like 1 could do)

I have started understanding about Auto Enter but this is more of a Validation Issue correct? Does it need to be a Value List or can a calculation do the trick? I guess scripting could be this type of sentinel as well?

I am afraid your example doesn't make much sense to me. In general, you should use field validation to ensure data integrity. Scripting is NOT an adequate substitute, though you may use it in addition to validation (since the validation error message can be rather intimidating).

 

Within field validation options you'll find various presets, such as 'Not empty' and 'Member of value list' (you can turn on more than one). If no combination of presets satisfies your business rules, you can roll your own and validate by calculation.

 

I don't see why text entries of "NULL", "FALSE" or "Empty" would be objectionable?

For the purpose doing doing other things with relationships like filtering and using ExecuteSQL I have ran in to trouble when a field is Empty, "", or False. Thanks

A field that contains the text "Empty" is not empty. Similarly, a field that contains the text "True" is not True.

 

You should make a distinction here between text fields and number fields. A number field is False if it is empty or contains a value of 0. A text field will evaluate to False if the text contains no digits other than 0 - but I fail to see why this should cause any trouble with relationships, filtering or SQL.