$ /opt/perl/5.8.0/bin/perl x.pl 
<<< 
HTML1
 >>>
<<<  CODE1  >>>
<<< HTML2
 >>>
<<<  CODE2  >>>
<<< HTML3 >>>

$ /opt/perl/5.6.1/bin/perl x.pl 
<<< 
HTML1
 >>>
<<<  CODE1  >>>
<<< HTML3 >>>

$ /opt/perl/5.6.0/bin/perl x.pl 
<<< 
HTML1
 >>>
<<<  CODE1  >>>
<<< HTML2
 >>>
<<<  CODE2  >>>
<<< HTML3 >>>

$ /opt/perl/5.005_03/bin/perl x.pl 
<<< 
HTML1
 >>>
<<<  CODE1  >>>
<<< HTML2
 >>>
<<<  CODE2  >>>
<<< HTML3 >>>