Include a template from a template

Hello,

In our RT installation we are working with HTML templates that always include a sidebar with quick access to the RT system and some quick information (like ID, Status, Owner etc). Currently I copy and paste the code for the sidebar into all templates, which is quite cumbersome. Can I from a template execute some perl code and include another template? This would really reduce the time it takes to customize the templates.

Thanks,
Tobias