Wss3sdk: site and list content type

You can create content types at the site level. This type of website content is used as a template independent of any list or library. The website content type is valid for all sub-websites. For example, if we create a site content type in the root site of the website set, the site content type is valid for all sites in the site set, you can add a user to any list of the website.
Inheritance of content types
When we create a site content type, it is available in all sub-sites. At this point, the website content type can be added to the list of websites, but is not actually added to any specific website list.

Note::
You must have at leastWebsite designerAccess permission. Specifically, you must have the permission to add and customize pages to the management list of the website to which the content type belongs.

To add a content type to the list, you must haveList AdministratorPermission.

When you add a website content type to the list, Windows SharePoint Services 3.0 copies a local copy of the website content type to the list. This local instance is called the list content type and only applies to the copied list.

Because Windows SharePoint
Services stores a copy of the website content type as a list content type of the list that adds the website content type, you can change the list content type without affecting the website
Capacity Type. Changes to the list content type are limited to this list and do not affect the website content type, or any other types of content inherited from the same website content type.

This link is displayed. Two website content types, memo and spec, are defined in a website. When the spec content type is added to a list in the Child site, Windows SharePoint Services copies an instance of the website content type to this list.

The memo content type can also be added to a list of sub-websites. However, this content type is not added to the list, so there is no copy of it in the list.