[antlr-interest] Understanding the "the following token definition is unreachable" warning

[Lloyd Dupont]

In ANTLR v3.0 I just started to create a new grammar (I'm using ANTLR works 1.0)
Here is the whole grammar file:
====
grammar SIPGrammar;

options 
{ 
 language=CSharp;
 output=AST;
}

message : LWS+;


LWS : (WSP* CRLF) => (WSP* CRLF) WSP+
 | WSP+;
protected WSP : ' ' | '\t';
protected CRLF : '\r\n';
====

When I compile it tell me the following warning message:
======
[14:39:47] warning(208): C:\...\SIPGrammar.g:14:11: The following token definitions are unreachable: WSP
======
Now, the position 14:11 is just before W in "protected WSP"
What the heck does that means?

When I try the interpreter everything seems to work out well...
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