title: How do you determine if a Char is a Letter from A-Z?
body: <p>How do you determine if a letter is in the range from A-Z or Digit 0-9?  We are getting some corrupted data "I_999Š=ÄÖÆaðøñòòñ".</p>
  
  <p>I thought I could use Char.IsLetterOrDigit("Š") to ID the corrupted data from "I_999Š", but unexpectedly this is returning true.  I need to trap this, any thoughts?</p>