From Textpattern CMS User Documentation
The Presentation tab is a main-level tab composed of various sub-tabs for each of Textpattern's presentational building-blocks; in other words, the things that control the location, layout and appearance of your content. The sub-tabbed areas are indicated below and described in detail.
Note: It can -- and has been -- argued that Forms are more a content item than a presentational item, as they more often than not represent packaged chunks of content, and thus should exist in the Content tab to strengthen semantic understanding. Regardless, the argument is trivial and Forms are powerful regardless of which admin-side vector you access them.