... address or an Internet URL;ifitdoesn’tmatchthisdefinition,thepageisconsidered invalid. Listing 4- 13 shows you how to validate what is input into a text box by making sureit is in the form of ... against valuesor calculations performed in the data tier (for example, in a database), or to make sure that the user’sinput validates against some arithmetic validation (for example, determining ... values:❑Equal❑NotEqual❑GreaterThan❑GreaterThanEqual❑LessThan❑LessThanEqual❑DataTypeCheck2 05 Evjen c04.tex V2 - 01/28/2008 12:45pm Page 210Chapter 4: Validation Server ControlsFigure 4 -5 Listing 4- 13: Making sure the text-box value is an e-mail addressEmail:< asp: TextBox...