">Proper tail recursion</a></td></tr>
 <tr><td valign="top" align="left">4</td><td colspan="4" width="100%"><a href="r5rs-7.html#Expressions">Expressions</a></td></tr>
 <tr><td></td><td valign="top" align="left">4.1</td><td colspan="3" width="100%"><a href="r5rs-7.html#Primitive-expression-types">Primitive expression types</a></td></tr>
 <tr><td></td><td valign="top" align="left">4.2</td><td colspan="3" width="100%"><a href="r5rs-7.html#Derived-expression-types">Derived expression types</a></td></tr>
 <tr><