\indexisarreg;

--- a/doc-src/isar.sty	Sun Aug 22 21:14:28 1999 +0200
+++ b/doc-src/isar.sty	Sun Aug 22 21:14:44 1999 +0200
@@ -13,6 +13,7 @@
 \newcommand{\indexisarcmd}[1]{\index{#1 (command)|bold}}
 \newcommand{\indexisarmeth}[1]{\index{#1 (method)|bold}}
 \newcommand{\indexisaratt}[1]{\index{#1 (attribute)|bold}}
+\newcommand{\indexisarreg}[1]{\index{#1 (register)|bold}}
 
 \newcommand{\isarcmd}[1]{\isarkeyword{#1}}
 \newcommand{\isartrans}[2]{#1 \mathbin{\,\to\,} #2}