src/Pure/Isar/token.scala

     val LONG_IDENT = Value("long identifier")
     val SYM_IDENT = Value("symbolic identifier")
     val VAR = Value("schematic variable")
     val TYPE_IDENT = Value("type variable")
     val TYPE_VAR = Value("schematic type variable")
-    val NAT = Value("number")
+    val NAT = Value("natural number")
+    val FLOAT = Value("floating-point number")
     val STRING = Value("string")
     val ALT_STRING = Value("back-quoted string")
     val VERBATIM = Value("verbatim text")
     val SPACE = Value("white space")
     val COMMENT = Value("comment text")