QuickForm: Blocknames in ITDynamic

Hi! In ITDynamic_example.php not all the elements/groups are assigned to blocks at the end of the script. For example the text-input itxtTest isn't assigned to any block within the script. Is there a naming convention for blocks (like qf_text) that the renderer uses for text-input-elements? Furthermore, what is the secret behind the *_loop tags for blocks? Thanks for your help! -- Cheers! Marco