if tag is a command tag. If wraps a set of command tags with a condition. When the condition defined in its attribute evaluates to true, the command tags in its body and in the then tag will be executed. Else the command tags in else tag will be executed.

The syntax for if tag is:

  <if value1="expression1" op="comparator" value2="expression2">
     <!-- add other command tags here --!>
     <then>
        <!-- add other command tags here --!>
     </then>
     <else>
        <!-- add other command tags here --!>
     </else>
  </if>

if tag shares most of the attributes with assert tag.

The attributes value1, op and value2 are the same as assert tag.