The <TMPL_LOOP> tag is a bit more complicated than <TMPL_VAR>.  The
<TMPL_LOOP> tag allows you to delimit a section of text and give it a
name.  Inside this named loop you place <TMPL_VAR>s.  Now you pass to
param() a list (an array ref) of parameter assignments (hash refs) for
this loop.  The loop iterates over the list and produces output from
the text block for each pass.  Unset parameters are skipped.  Here's
an example:

 In the template:

   <TMPL_LOOP NAME=EMPLOYEE_INFO>
      Name: <TMPL_VAR NAME=NAME> <br>
      Job:  <TMPL_VAR NAME=JOB>  <p>
   </TMPL_LOOP>


 In the script:

   $template->param(EMPLOYEE_INFO => [ 
                                       { name => 'Sam', job => 'programmer' },
                                       { name => 'Steve', job => 'soda jerk' },
                                     ]
                   );
   print $template->output();

  
 The output in a browser:

   Name: Sam
   Job: programmer

   Name: Steve
   Job: soda jerk

As you can see above the <TMPL_LOOP> takes a list of variable
assignments and then iterates over the loop body producing output.