text box has to allow special characters

Hi Friends,
I put the regular expression validator  for textbox like this i.e it allows characters and numbers also,
ValidationExpression="[a-zA-Z0-9]*but I want to allow the special characters like  -,:" " and etc
what is the validationexpression I have to put that textbox has to allow the special symbols
Please any one give some examples
 
Regards
Geeta 
 
 
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