added internal;

--- a/src/Pure/attribute.ML	Fri Jul 24 13:53:04 1998 +0200
+++ b/src/Pure/attribute.ML	Fri Jul 24 14:53:23 1998 +0200
@@ -28,8 +28,10 @@
   val untag: tag -> 'a attribute
   val lemma: tag
   val assumption: tag
+  val internal: tag
   val tag_lemma: 'a attribute
   val tag_assumption: 'a attribute
+  val tag_internal: 'a attribute
 end;
 
 structure Attribute: ATTRIBUTE =
@@ -91,8 +93,10 @@
 
 val lemma = ("lemma", []);
 val assumption = ("assumption", []);
+val internal = ("internal", []);
 fun tag_lemma x = tag lemma x;
 fun tag_assumption x = tag assumption x;
+fun tag_internal x = tag internal x;
 
 
 end;