diff --git a/docs/zr_manual.htm b/docs/zr_manual.htm
index 9b1165d..1385a5c 100644
--- a/docs/zr_manual.htm
+++ b/docs/zr_manual.htm
@@ -16,7 +16,7 @@
 
 <p class="headerinfo">Targets plugin version 3.0.0 Beta 2, (not released)<br />
 Written by Richard Helgeby</p>
-<p class="headerinfo">Manual last modified: 2009.10.20</p>
+<p class="headerinfo">Manual last modified: 2009.10.30</p>
 
 <h2>Index</h2>
 
@@ -2340,9 +2340,15 @@ tune game balance.</p>
 	</tr>
 	<tr>
 		<td class="indent" colspan="2">
-			<p>Mother zombie ratio. Every random N-th player is infected. In this case it's 5 where
-			every fifth player will be infected. If it's set to 0 there will be only 1 mother zombie
-			every time.</p>
+			<p>Mother zombie ratio. Every random <em>n</em>-th player is infected. In this case it's
+			5 where every fifth player will be infected. If it's set to 0 there will be only 1 mother
+			zombie every time.</p>
+			<p>Note that this is NOT a percentage value. The ratio 5 does not mean 5%, but every
+			fifth player. To get the percentage you need to do <em>ratio</em> / <em>player slots</em>.
+			Like 5 / 24 = 0.20 &rArr; 20% infection rate.</p>
+			<p>Conversion formula from percent to ratio:</p>
+			<blockquote><p><em>ratio</em> = (<em>percent</em> / 100) * <em>player slots</em></p></blockquote>
+			<p>Decimals are stripped from the ratio because it's a integer value.</p>
 			<p>Options:<br />
 			0 or a positive number up to max server slots</p>
 		</td>