What are categories?

When you work with a collection which includes material belonging to different subjects, you will want to keep different subjects in different sections of the knowledge tree (in the contents window). You will also want to design a different look for items related to literature, and a different look for questions related to mathematics. For example, you will use pictures to illustrate your anatomy branch, sounds to illustrate your foreign language section, spell-pads to make your spelling section work best, etc.

To help you keep different subjects in one collection, SuperMemo introduces the concept of a category. A category is a section of the knowledge tree. It is used for keeping material related to a single subject. Elements added to a given category may use their own template that determines their look (e.g. images, sounds, colors, fonts, sizes of text fields, number of shape components, etc.). It is highly recommended that you learn about templates before using categories. See: Using templates

Once you understand the concept of the category, it will become very easy to manage a large number of items belonging to entirely different areas of knowledge.

Creating a category

You can easily create a new category using the following steps:

1. choose Edit : Create category
2. choose a branch in the knowledge tree where a category should be inserted and click Next
3. type in Category name (e.g. geography, biology, etc.) and click Next
4. if you want your category to use a template created earlier use Change buttons to select a new template. If you are not sure about templates, click Finish and SuperMemo will use default templates for your category. You can change templates later by means of View : Categories. Template for items will determine the look of your question-answer items in the category. You can also choose other template formats for items (e.g. occlusion test, multiple choice test, etc.). Template for topics will determine how your category articles will look like (e.g. when you import them with Ctrl+Alt+N in incremental reading)

Tips:

• If your Tools toolbar is visible, in the category combo-box, you will see that your new category became the default category. This means that choosing Add new will add new items to your new category.
• Press Alt+A if you want to add some elements to your new category. If you click Contents, you will see your newly added elements become children of the root category element (i.e. the one created with Edit : Create category).
• If you define a new look for your category items, you can press Ctrl+Alt+M to save the look as the default template for the current category (Template : Save as default on the element menu)

Category properties

If you would like to change category properties, choose Search : Categories on the main menu. You will see the category registry with all categories that you have defined until now:

Each category in the registry is characterized by the following properties (compare with the picture above):

• name - the name of the category (e.g. Geography). All category names are displayed on the left in the category registry. Category names are unique. If you try to create second Geography category, SuperMemo will change the new name (e.g. to Geography# or Geography@)
• template - template that determines the look of items in the category
• root - the element which is the ancestor of all elements included in the category (i.e. all elements in the category are descendants of the root). This is the same element that have been added when using Edit : Create category 
• hook - the element to which new category elements are added as children when you choose Add new (e.g. by pressing Alt+A). This element is chosen automatically by SuperMemo and you do not have to change it. Hook is either equal to the root (e.g. at the beginning of the category's life) or is a descendant of the root (when the root already contains many children). Note that Add new adds elements to the hook of the current category (as selected in the category combo box on the Tools toolbar). Once the number of children in a given hook exceeds a defined limit, a new hook node is chosen automatically by SuperMemo
• ordinal - default ordinal in the category (use zero to make SuperMemo generate ordinals corresponding with the number of elements in the collection)
• forgetting index - default value of the requested forgetting index in the category (use zero to make the category reuse the default forgetting index defined with Tools : Options : Learning : Forgetting index)
• auto-apply - property which determines if Apply template is to be used automatically on elements transferred from another category to the category in question (as with Ctrl+Shift+P). If auto-apply is checked, the template will be applied automatically. If it is unchecked, template will not be applied. If it is grayed, SuperMemo will prompt you before applying the category template (use the grayed option if you are not sure which one is appropriate)
• topic template - template used for topics in the category
• task template - template used for tasks in the category

Using category registry

The category registry can be opened with Search : Categories on the main menu. Category registry is useful in the following circumstances:

1. If you want to change the name of a category, use Rename in the category registry
2. If you want to change the template used for items in the category, click the Template button in the category registry, select a new template from the template registry and choose Accept
3. To delete a category, choose Delete in the category registry
4. To decide if template should be applied automatically when moving items into the category , use auto-apply button

It is not recommended to change Root or Hook manually (unless you fully understand the way SuperMemo builds category folders under the category root)

Summary

Here is the typical way of working with categories:

1. Use Edit : Create category to create a category
2. Use Ctrl+Alt+M to save the default item template (or use Search : Categories to change category templates)
3. To start adding items to another category (e.g. to start working with Chemistry after finishing your work with Geography), choose the new category in the category combo-box on the Tools toolbar
4. To move items from To Do category to a target category (e.g. Chemistry), pres Ctrl+Shift+P and change the category in the Category combo and choose OK

See also: FAQ: Categories in SuperMemo