Feed and subscription list detection algorithm¶
Neither RDF+FOAF nor the iGoogle exported settings formats support embedded subscription lists. This detection algorithm only applies to OPML subscription lists.
Many services and softwares output OPML subscription lists with slight
variations. listparser attempts to correctly determine whether an
outline element is attempting to reference a feed or subscription
list. As an example, although feeds should be indicated using
type="rss" (no matter the format), some services refer to feeds
type="link", others indicate that the feed is Atom-formatted
type="pie", and still others fail to include a
attribute at all! Therefore it is necessary to make educated guesses.
outline element contains an
xmlUrl attribute, the
outline is assumed to represent a feed. listparser will also accept
xmlURL, or indeed any capitalization combination.
type is ignored entirely in making the decision, with one
notable exception (see below).
Subscription list detection¶
outline element has a
url attribute and
type="include", listparser assumes that it has found a
subscription list. Additionally, if it has an
xmlUrl attribute and
type="source", it is also considered a subscription list.
Although the “include” value was only introduced in OPML 2.0,
listparser ignores the OPML version entirely. Additionally, despite the
OPML 2.0 requirement that the
url value of “link”
elements must end in “.opml” to be considered an OPML file, listparser
ignores the URL suffix when detecting whether the element is a