title: Match a specific expression across multiple lines with RegularExpressionValidator
body: <p>I'm trying to build a regular expression to match the text typed by a user in a multineline input</p>
  <p>The text should be on that shape:</p>
  <pre><code>Class 1: Exemple1 
  Class 2: Exemple2
  ....
  </code></pre>
  <p>Every line must respect that syntax.</p>
  <p>I managed to create the regex for a single line but i can't find a proper solution to extend it to a multilines version</p>
  <pre><code>&lt;asp:RegularExpressionValidator ID=&quot;RegularExpressionValidator&quot; runat=&quot;server&quot;
   ErrorMessage=&quot;This is wrong!&quot; ValidationExpression=&quot;^[Class]+\s[0-9]+:+\s+[a-zA-Z]+$&quot;
  ControlToValidate=&quot;txtUserInput&quot;&gt;&lt;/asp:RegularExpressionValidator&gt;&lt;br /&gt;
  </code></pre>
  <p>Thank you in advance for your help</p>