Clarify what is meant with "whole numbers".

birkenfeld · birkenfeld · commit 7da4edac2855 · 2005-09-04T18:30:19.000Z
diff --git a/Doc/ref/ref3.tex b/Doc/ref/ref3.tex
@@ -165,7 +165,8 @@ \section{The standard type hierarchy\label{types}}
 
 \begin{description}
 \item[Integers]
-These represent elements from the mathematical set of whole numbers.
+These represent elements from the mathematical set of whole numbers
+(positive and negative ones).
 \obindex{integer}
 
 There are three types of integers:
