For clarity add:

Initial Rep       @Mode        Expression          Value        Final Rep 
------------------------------------------------------------------------- 
<a/>              Replace      /                   <a'/>        <a'/> 
<a/>              InsertBefore /                   <a'/>        fault 
<a/>              InsertAfter  /                   <a'/>        fault 
                  InsertBefore /                   <a/>         <a/> 
                  InsertAfter  /                   <a/>         <a/> 
<a/>              InsertBefore /a/b                <b/>         <a><b/></a> 
<a/>              InsertAfter  /a/b                <b/>         <a><b/></a> 


For each "/" in the expression column replace it with
"/ or /*"  to make it clear that they're the same.