title: antlr4 token recognition error at: '$'
body: <p>Trying to build a grammar for PowerScript language. I split the language in several parts and everything seems to be working except for the simple headers. It seems that the $ simbol can't be recognized. Could anyone help me a little? ( I just copy the small example I'm trying)</p>
  
  <pre><code>grammar PowerScript;
  
  compilationUnit :   Header EOF;
  
  fragment 
  Header  : ID '.' ID;
  
  ID : [a-zA-Z0-9$_]+ ;
  </code></pre>
  
  <p>test file just contains:</p>
  
  <pre><code>$PBExportHeader$n_logversion.sru
  </code></pre>
  
  <p>Thanks</p>