什麼是OPML?

OPML

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File extension:
.opml




MIME type:
text/xml, text/x-opml




Type of format:
Outline




Extended from:
XML
OPML (Outline Processor Markup Language) is an XML format for outlines. Originally developed by Radio UserLand as a native file format for an outliner application, it has since been adopted for other uses, the most common being to exchange lists of RSS feeds between RSS aggregators.
The OPML specification defines an outline as a hierarchical, ordered list of arbitrary elements. The specification is fairly open which makes it suitable for many types of list data.
Alternative specifications
OPML is being used more widely because of its ties to RSS. It has also been incorporated into PIM applications.
Alternative specifications have been proposed. One such specification is OML. While very similar to OPML, OML forces a separation between data presentation and content; it also treats textual content as an XML element. OPML, by contrast, treats textual content as an XML attribute, which limits its extensibility and precludes the possibility of nested XML elements within textual content, but makes OPML somewhat simpler to code by hand in a text editor.
Another specification that has been proposed is XOXO. XOXO treats textual content as an XML element rather than an XML "attribute". XOXO is easier than OPML to code by hand in a text editor, since it can be easily previewed in any web browser.