filter

The filter of source section.

<filter
    type="(page|section|list|inbox)"?
  />

type="(page|section|list|inbox)" (optional)

The type of the filter.

Allowed values are:

page (default): Filters if the article is added to the active page of the section.
section: Filters if the article is added to the section.
list: Filters if the article is added to any of the lists of the section.
inbox: Filters if the article is added to any of the inboxes of the section.