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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 can be seen as a tool for building a section of the knowledge tree. One category is used for adding material related to one 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 on the main menu
  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 different template use the 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)


Using Categories

When you click the Add New button, the new element is created in the location and using the template determined by the current category as chosen in the drop down list of the combo box in the Tools toolbar.
While you are creating new elements, if you decide you want this element to go into a different major portion of the knowledge tree then all you have to do is change the current category before creating the new element. That new element will then be placed in the appropriate location of that other section of the tree and the appropriate template will be used. If you start creating elements for a different subject then you just change the category again.
In order to achieve this convenience it may be necessary to create a rather large set of categories, especially if you keep all your information in one collection. You may want to create categories for more than just each major "category" of information. You may want to create one for each type of question you might ask for each different subject. You may even want to break your subjects down into smaller sub-topics so that you can choose an appropriate category to get the new elements closer to other related information.

In incremental reading, instead of frequently changing categories while adding new items, you are more likely to use a big TO DO category, and move individual items to their final categories only when they are finished in the incremental learning process (e.g. with Ctrl+Shift+P).


Category properties

If you would like to change category properties, choose Search : Categories on the main menu, or click the yellow button to the right of the categories drop down list in the Tools toolbar. You will see the category registry with all categories that you have defined for the collection:

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

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 a 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). Choosing it wrongly may result in an unexpected rearrangement of your entire knowledge tree (SuperMemo rebuilds the category tree when you add too many elements to its hook node).


While it may seem complicated at first, with categories, it is really quite simple to create new elements. You can just keep pressing the Add new button confident that the new element is going to go right at the end of the list of elements under the hook node of the category you are currently working with. If you decide to look at some other element in the knowledge tree, you can go right back to adding new elements and they will still be added where they were being added before. This way, if you are reviewing elements in the tree and decide to add another element, it will go at the end of the list of elements for that category where it belongs.


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