'let': replaced 'as' by 'and';

--- a/doc-src/IsarRef/pure.tex	Mon Apr 03 21:05:07 2000 +0200
+++ b/doc-src/IsarRef/pure.tex	Tue Apr 04 12:31:48 2000 +0200
@@ -850,7 +850,7 @@
 does not support polymorphism.
 
 \begin{rail}
-  'let' ((term + 'as') '=' term comment? + 'and')
+  'let' ((term + 'and') '=' term comment? + 'and')
   ;  
 \end{rail}