Users, who create texts (stories), aimed to be included in articles later in the article copy flow, have to select the appropriate type for such stories, otherwise, stories will not qualify.
You predefine types of article elements in a system-wide setting - XML schema. Available types may be: head, summary, body, photo, multimedia, url, graphic, and similar. The number and names of types is customizable.
When an user creates an article element, such list of types allows him to select the appropriate one. The type of a text can be also changed later, by the Properties dialog box.
The schema also defines how many elements of certain type can be included in an article. For example, you can define that an article can have no more than one head and body element, but can have as many as you want photo and multimedia elements. Such control is supported by all operations which insert elements into an article.
The Allowed types box in the Select text dialog box, and the related list of stories, changes dynamically. It contains the list of element types that are not yet assigned to the current article, or are not reached the limit of assignment (i.e. multiple element of that type are allowed).
Same considerations apply to any other element, such as photos, multimedia and URL.