# 8. Default Codeunits

The platform ships with a couple default codeunits, that help manage the CMS data.

### Basic Menu

Name: com.tsnocode.core.cms.BasicMenu

Generates a dynamic menu, with option of one layer of sub-element, and marks the active page.

### Page handler

Name: com.tsnocode.core.cms.PageEventHandler

Helps maintain redirects, when a pages url changes, by automatically added the old url to the redirects entity.

### Media handler

Name: com.tsnocode.core.cms.MediaEventHandler

Helps write images and videos to disk, and down sampling videos.

### Preview page

Name: com.tsnocode.core.cms.ShowPage

Resets the cache and shows a page.