With the Content Block iPart, you can empower authorized users to create and edit content directly on a page, without using Surf-to-Edit or accessing Tools. Through iPart configuration, you can allow users to insert HTML content, add attachments, create child pages, and submit replies. At its simplest, a content block can be HTML that is read-only unless the user has permissions to see the edit command. At its most complex, a block can act as a message board with multiple posts, child posts, and replies. You can limit the number of posts to a set number, or you can leave it at the default (zero), which lets it grow indefinitely.
How groups own content
The content created with a Content Block iPart is owned by the Uniform Item associated with the page that contains the iPart. Likewise, the only content displayed is content owned by the page’s Uniform Item. The Content Block currently works best with the Group landing page, where it can be used with the Uniform Item for groups. A page’s Uniform Item is determined by the iUniformKey parameter passed to the page in the URL.
For example, assume that you have a content record that displays when a user clicks a search result link for a Committee, and it contains a Content Block iPart configured to display content tagged as Announcement. Now a Content Editor wants to add an announcement for the Planning Committee. After searching for it, he selects the result and goes to the page. The search link sends the iUniformKey for the Planning Committee to the content record through the URL. The Content Block iPart then displays any announcements (the tag) for the Planning Committee (the Uniform Item). When he adds his new content, it is tagged as an Announcement and is owned by the Planning Committee.
Tagging to filter content
To control what content appears in a Content Block, you create tags specific to ContentBlock Items and apply those tags to specific instances of the iPart. For example, if you want to create a new blog for Tim Jones, you could create a ContentBlock tag such as blog-JonesT, place a new Content Block iPart on a content record, and configure the iPart to display the tag blog-JonesT. Now the content that Tim authors in this blog will be unique to his blog, if you do not apply this tag anywhere else:

Content created with anything other than a Content Block iPart will not be displayed, even if it has the same tag. For example, a content record containing HTML tagged with News will not show up in a Content Block that is also using the News tag.
Best practice: Plan for and create the tags you want to use before configuring your Content Block iParts. Content can seem to disappear if you change the tags assigned to a content block already in use, because it no longer matches the tag set currently configured.
Creating a message board
Only users with the Content Editor permission may create posts and children, but any authenticated users can reply to a post and edit or delete their own replies.
To use the Content Block as a message board with multiple posts, child posts, and replies, make use of the following configuration options:
■ Maximum items to display - Choose the maximum number of posts that will be displayed; 0 indicates an unlimited number of posts.
■ Display mode - Expanded display mode will display replies and child posts in-line, while Summary mode only shows replies and child posts when the post is opened.
■ Allow child posts - Allow Content Editors to add a child post to existing content.
■ Allow replies to posts - Allow authenticated users to reply to posts; you may indicate whether to allow HTML and/or attachments in the replies.

Content Block iPart set up as a discussion board