diff -r bd140638915f -r 8bda15db8a3d ssm-en.xhtml
--- a/ssm-en.xhtml	Wed Aug 24 00:11:41 2016 +0200
+++ b/ssm-en.xhtml	Wed Aug 31 11:45:16 2016 +0200
@@ -47,15 +47,16 @@
 			</li>
 		</ul>
 
-		<h2>Compatibilible with itself</h2>
+		<h2>Compatible with itself</h2>
 		<ul>
-			<li>focus on backward compatibility</li>
-			<li>don't broke things</li>
-			<li>incompatible changes must be planned and announced in advance</li>
+			<li>Focus on backward compatibility. Newer version should work as a drop-in replacement.</li>
+			<li>Don't broke things – rather postpone the release date than deliver a faulty product.</li>
+			<li>Don't remove features unless they are really obsolete, unused or unrepairably broken.</li>
+			<li>Incompatible changes must be planned and announced in advance. <!--Major/minor/patch numbers must be increased according to the Semantic versioning.--></li>
 			<li>upgrade scripts + upgrade documentation</li>
 		</ul>
 
-		<h2>Compatibilible with others</h2>
+		<h2>Compatible with others</h2>
 		<ul>
 			<li>use open standards (protocols, formats) if they exist</li>
 			<li>define own open standards if needed