todo-mode: Levels of Organization

 
 1.1 Levels of Organization
 ==========================
 
 In Todo mode each todo list is identified with a named category, so you
 can group together thematically related todo items.  Each category is
 stored in a file, which thus provides a further level of organization.
 You can create as many todo files, and in each as many categories, as
 you want.
 
    All todo files reside in a single directory, whose location is
 specified by the user option ‘todo-directory’.  This directory may also
 contain other types of Todo files, which are discussed later (SeeTodo
 Archive Mode and SeeTodo Filtered Items Mode).  When you use a
 Todo mode command to create a todo file, the extension ‘.todo’ is
 automatically added to the base name you choose (as a rule, this name is
 also used for the other types of Todo files, which have their own
 extensions).  As a user, you only have to deal with the base name of a
 Todo file.
 
    When you create a new todo file, you must also add at least one
 category to it, and each todo item belongs to a category.  It is not
 possible to have an uncategorized todo list, but you can always make a
 catch-all category with a generic name like “Todo”, which is in fact the
 default name assigned to the first category when you create a new todo
 file, if you don’t provide a different name; you can change the default
 by customizing ‘todo-initial-category’.
 
    The most basic level of organization is the todo item itself, since
 it contains the information about what you want to do.  As detailed in
 subsequent sections of this manual, most Todo mode commands and user
 options concern ways of classifying and deploying this information by
 associating various kinds of metadata with it, e.g., the category it
 belongs to, its priority, whether it is to be included in the Emacs
 diary, date and time stamps, whether it is done or still to do.