diff --git a/src/parser/A3t.cpp b/src/parser/A3t.cpp
index ad7a445ef..b03a9561a 100644
--- a/src/parser/A3t.cpp
+++ b/src/parser/A3t.cpp
@@ -71,6 +71,7 @@ Tree* A3t::parse ()
   findAttributeModifier ();
   findUUIDList ();           // Before findIdSequence
   findIdSequence ();
+  findOperator ();
 
   validate ();
 
@@ -611,6 +612,45 @@ void A3t::findUUIDList ()
   }
 }
 
+////////////////////////////////////////////////////////////////////////////////
+void A3t::findOperator ()
+{
+  // Find the category.
+  std::pair <std::multimap <std::string, std::string>::const_iterator, std::multimap <std::string, std::string>::const_iterator> c;
+  c = _entities.equal_range ("operator");
+
+  // Extract a list of entities for category.
+  std::vector <std::string> options;
+  std::multimap <std::string, std::string>::const_iterator e;
+  for (e = c.first; e != c.second; ++e)
+    options.push_back (e->second);
+
+  std::vector <Tree*>::iterator i;
+  for (i = _tree->_branches.begin (); i != _tree->_branches.end (); ++i)
+  {
+    // Parser override operator.
+    if ((*i)->attribute ("raw") == "--")
+      break;
+
+    // Skip known args.
+    if (! (*i)->hasTag ("?"))
+      continue;
+
+    std::string raw = (*i)->attribute ("raw");
+
+    std::vector <std::string>::iterator opt;
+    for (opt = options.begin (); opt != options.end (); ++opt)
+    {
+      if (*opt == raw)
+      {
+        (*i)->unTag ("?");
+        (*i)->tag ("OP");
+        break;
+      }
+    }
+  }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Validate the parse tree.
 void A3t::validate ()
diff --git a/src/parser/A3t.h b/src/parser/A3t.h
index bac5293d6..2fa8bda28 100644
--- a/src/parser/A3t.h
+++ b/src/parser/A3t.h
@@ -53,6 +53,7 @@ private:
   void findAttributeModifier ();
   void findIdSequence ();
   void findUUIDList ();
+  void findOperator ();
   void validate ();
 
 private:
diff --git a/src/parser/args.cpp b/src/parser/args.cpp
index ca8ea4671..af1af0e43 100644
--- a/src/parser/args.cpp
+++ b/src/parser/args.cpp
@@ -108,6 +108,29 @@ int main (int argc, char** argv)
     a3t.identity ("modifier",   "word");
     a3t.identity ("modifier",   "noword");
 
+    // Operators.
+    a3t.identity ("operator",   "and");
+    a3t.identity ("operator",   "or");
+    a3t.identity ("operator",   "xor");
+    a3t.identity ("operator",   "<=");
+    a3t.identity ("operator",   ">=");
+    a3t.identity ("operator",   "!~");
+    a3t.identity ("operator",   "!=");
+    a3t.identity ("operator",   "=");
+    a3t.identity ("operator",   ">");
+    a3t.identity ("operator",   "~");
+    a3t.identity ("operator",   "!");
+    a3t.identity ("operator",   "_hastag_");
+    a3t.identity ("operator",   "_notag_");
+    a3t.identity ("operator",   "-");
+    a3t.identity ("operator",   "*");
+    a3t.identity ("operator",   "/");
+    a3t.identity ("operator",   "+");
+    a3t.identity ("operator",   "-");
+    a3t.identity ("operator",   "<");
+    a3t.identity ("operator",   "(");
+    a3t.identity ("operator",   ")");
+
     Tree* tree = a3t.parse ();
     if (tree)
       tree->dump ();