diff -r 5ec4d21889d6 -r 64f76b974a8d doc-src/System/basics.tex
--- a/doc-src/System/basics.tex	Fri Apr 08 18:43:39 2005 +0200
+++ b/doc-src/System/basics.tex	Sat Apr 09 15:34:38 2005 +0200
@@ -186,11 +186,17 @@
 \item[\settdx{ISABELLE_DOCS}] is a colon separated list of directories with
   documentation files.
   
+\item[\settdx{ISABELLE_DOC_FORMAT}] specifies the preferred document format,
+  typically \texttt{dvi} or \texttt{pdf}.
+  
 \item[\settdx{DVI_VIEWER}] specifies the command to be used for displaying
   \texttt{dvi} files.
   
+\item[\settdx{PDF_VIEWER}] specifies the command to be used for displaying
+  \texttt{pdf} files.
+  
 \item[\settdx{PRINT_COMMAND}] specifies the standard printer spool command,
-  which is expected to accept PS files.
+  which is expected to accept \texttt{ps} files.
   
 \item[\settdx{ISABELLE_TMP_PREFIX}*] is the prefix from which any running
   \texttt{isabelle} process derives an individual directory for temporary