Let me walk you through everything you need to know about OPML files. We‘ll explore what they are, why they exist, a bit of history, how software utilizes them today, and even how to create OPML yourself.
Ready to learn? Let‘s dive in!
What Exactly Are OPML Files?
OPML stands for "Outline Processor Markup Language." Essentially, these files provide a standardized format for storing outline data using XML markup.
Outlines are tree-structured lists that organize information hierarchically. OPML gives us a universal way of exchanging outlines between different programs.
The technology originated in 2000 from UserLand Software and creator Dave Winer. It was included in their Radio UserLand blogging suite as a way to import/export RSS feed reading lists. Due to OPML‘s flexibility, many other outlining tools also began adopting it.
Now it serves as interoperability glue enabling outlines and vital data to flow easily across platforms and devices. Understanding OPML can save time and effort in your digital life.
In this guide, we‘ll unpack everything about this technology. Just continue scrolling to have all your OPML questions answered!
A Brief History of Digital Outlining
Let‘s quickly travel back in history to see where OPML and structured outlining came from…
1960s – Douglas Engelbart develops the oN-Line System, one of the first digital outliners ever created.
1980s – Commercial outlining tools like MORE and GrandView arrive for early home computers.
1998 – Standard XML format published for portable data exchange over the web.
That context sets the stage for OPML‘s debut…
XML provided the foundation for OPML to model outline architectures in a highly portable way across the emerging internet.
Let‘s explore more of the standard‘s specifics.
Key Capabilities of OPML Files
Within programming, OPML acts as a file format, data model, and processing syntax for tree hierarchies. For end-users however, OPML serves simpler functions:
- Import/Export Feed Lists – Easily migrate RSS reader subscriptions between apps. This was OPML‘s initial purpose.
- Exchange Notes – Move outlines containing drafted ideas or writings across devices.
- Manage Structured Data Lists – Port any list-based data structured as parent->child elements.
This combination of simplicity and flexibility is why OPML remains relevant decades later. Today it exists behind the scenes enabling you to seamlessly sync vital digital content.
Software Applications Supporting OPML
Many types of Mac, Windows, Linux, iOS and Android programs work with OPML files in some way:
- RSS Readers – Feedly, NewsBlur, Inoreader, Digg, etc.
- Email Clients – Mozilla Thunderbird, Postbox
- Note Apps – Simplenote, Apple Notes
- Mind Map Tools – XMind, MindView, MindNode
- Writing Tools – Scrivener
- Plus – Hundreds more niche programs
Anywhere outline data needs to be quickly transferred, you‘re likely to find OPML capabilities. It formed the backbone for migrating our digital lives to the cloud age.
An Inside Look at OPML Structure
As a format built on XML, OPML structure looks similar:
<opml version="1.0">
<head>
<title>My Feed List</title>
</head>
<body>
<outline text="Blogs">
<outline text="Lifehacker"/>
<outline text="Daring Fireball"/>
</outline>
</body>
</opml>We see familiar elements like <head>, <body>, <outline>, etc. It‘s like HTML for trees!
The <opml> tag indicates the root, while version declares format compliance. <outline> represents a single node that can nest children infinitely.
Head metadata and body hierarchy combine to fully model our outline data. Now let‘s compare format versions…
OPML Versions 1.0 vs 2.0
There have so far been two major iterations:
| OPML 1.0 (2000) | OPML 2.0 (2006) | |
|---|---|---|
| Creator | Dave Winer/UserLand | Dave Winer + Collaborators |
| Focus | RSS/Blog Ecosystem | Expanded Application Range |
| Sample Uses | Feed import/export | Legal cases, chat logs |
| Limitations | Few validation rules | Backward compatible with 1.0 |
Version 1.0 laid the groundwork by standardizing feed list exchange for early blog/newsreaders.
2.0 modernized and expanded OPML for more general outline architectures, but avoided breaking existing toolchains. It‘s still commonly used today.
Now let‘s shift gears to actually utilizing OPML yourself…
Opening and Converting OPML Files
Many digital outliners support directly exporting to or importing from OPML documents. But you can also interface with OPML files through:
- Viewers – Inspect raw XML outline structure
- Converters – Transform into Word, Excel, PDF, etc.
- Editors – Modify contents manually
For example, try importing an OPML file into Scrivener for instant draft notes. Or convert OPML to CSV format for easy spreadsheet viewing.
Don‘t worry, no specialized software knowledge is needed to leverage these capabilities!
Learning OPML Through Code Resources
For developers or digital enthusiasts who do want to dive deeper though, plenty of OPML technical resources exist:
- opml.org – Official standard documentation and schema references.
- opml.js – JavaScript parser by Dave Winer to integrate with apps.
- OPML Editor – Open source viewing/editing application.
- Plus – Spec listings on GitHub to study.
Digesting materials like these will give you an expert-level mastery of OPML format internals!
Closing Thoughts on the Standard
Today our digital lives overflow with outlines and hierarchies begging to be tamed – from project plans to video playlists.
OPML elegantly models these structures for frictionless migration between apps. The standard quintessentially meets designer Charles Eames‘ advice to "strive for simplicity but accept complexity."
Just remember that behind your effortless outliner syncing lies this powerful, yet often invisible data architecture!
I hope this guide gave you confidence for further exploring digital outlines and feeds. Let me know if you have any other OPML questions!
