Since blogs tend to be ephemeral in nature, it's standard to organize them by date in the form of monthly, weekly or daily archives. However, they can also be organized by topic or content using categories, tags or keywords. In doing so, entries can be effectively grouped together for the purposes of search from either the administrative interface or the published blog. Also, if configured to publish them, category groupings can be persisted in form of category archives.

Working with categories

When creating or editing an entry, authors can assign one or more existing categories to an entry. One category can be assigned as the primary category which will be listed along with the entry in the entry listings. In addition, multiple secondary categories can be assigned to cast a wider net and allow entries to span classification.

In creating categories, it's best if you make them as general and broad as possible and have very few of them. In this way, they provide a perfect counterbalance to the very specific and granual entry tags described later in this chapter. If you must make granular categories, it's best to do so using a hierarchical subcategory structure.

Note: While any author with entry creation or editing permission can assign an entry to a category, only those with "Add/Manage Categories" permission can create categories or perform the other management procedures listed in this section.

Managing the categories associated with a blog

To view and manage the list of categories associated with a blog, click on Manage > Categories from the main menu while working within any of your blogs in Movable Type. The Manage Categories page lists all categories and subcategories associated with your blog, the number of entries associated with each category, and the number of inbound TrackBacks that have been sent to that category directly by other blogs or sites. From the Manage Categories page you can create new top level categories, create new subcategories, promote or demote categories or subcategories, edit the details of categories and delete categories.

Creating a new top level category

• To create a new top level category, click on the "Create a new top level category" link at the top of the Manage Categories page.
• The system will allow you to quickly create a top level category, and will automatically assign it a basename for publishing archives to your blog.

Creating a new subcategory

• To create a new subcategory, click on the "Create" link on an individual category's row.
• The system will allow you to quickly create a subcategory as a child of your selected category, and will automatically assign it a basename for publishing archives to your blog.

Promoting or demoting a category or subcategory

• On the Manage Categories page, locate the category or subcategory that you wish to promote, demote or simply move to another parent category. Click on the "Move" link associated with that category.
• The system will display a hierarchical list of your categories and subcategories, with your selected category highlighted.
• Click the radio button that corresponds to the new desired parent category, or the "Top Level" radio button to make it a top level category. This will automatically move your category (and any of its subcategories) to your desired location.

Note: Once you've moved the desired category or subcategory, you'll need to publish your site for the change to take effect publicly. Click the publish icon in the main menu and follow the prompts.

Editing the details of a category

On the Manage Categories page, locate the category or subcategory that you wish to edit, and click on the category name to navigate to the Edit Category page. The Edit Category page allows you to edit the category label, basename, description, and TrackBack settings.

• Label: A category's label is the identifying name assigned to that category that serves as the identifier in any listing tables, category selection menus and on the published blog. It is displayed in templates using the tag <$MTCategoryLabel$>
• Basename: This is the identifying string for a category used in URLs and in the directory structure of your published blog files. As noted above, it is auto-generated upon creation of each category and remains the same even if the category's label changes, allowing you to do so without breaking incoming links to your archives. It is displayed in templates using the tag <$MTCategoryBasename$>
• Description: This field is optional, but gives you the ability to richly describe the category and its assigned entries. It is displayed using the tag <$MTCategoryDescription$>
• TrackBack settings: You can enable inbound TrackBacks for a category from any source, or specify TrackBack URLs to which you would like to send TrackBack pings whenever an entry is posted for that specific category.

Note: If you make changes to your Category details, you may need publish your site for the change to take effect publicly. Click the publish icon in the main menu and follow the prompts.

Deleting a category

• On the Manage Categories page, locate the category that you wish to delete, and select it by clicking on the checkbox on its row. You can delete multiple categories at once by clicking on more than one checkbox.
• Click the Delete button at the top of the page. The system will ask you to confirm your choice; click OK to delete the selected category or categories and remove all associated category assignments from your blog's entries.

Note: After you make delete one or more categories, you will need publish your site for the change to take effect publicly. Click the publish icon in the main menu and follow the prompts.

WARNING: When a category is deleted all entry assignments (but not the entries themselves) are removed. Additionally, if you have set the DeleteFilesAtRebuild directive in Movable Type's configuration file, the category archive pages for that category are removed from the filesystem. Like all deletions, this action is permanent and will render useless any bookmarks or incoming links that may exist to those pages.