Just wanted to add my two cents. It is certainly best practice to clear all errors, but I do not think warnings need to be cleared. They are just warnings that you should be aware of. It would be a good idea to review them, but I could list several if not dozens of scenarios where it's impossible to clear all the warnings. (That is, assuming you haven't edited the configuration of the System tab's settings for Validations)
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Dave Morris
Cano Ai
Atlanta, GA
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Dave Morris, 3Ci at Southern Company