Hdoc Converter Project

As we previously mentioned, the OPML standard focuses on providing a mean to organize information hierarchically. For this purpose it is quite efficient and is widely used among outliner software either for internal storage or export.

The simplicity of the OPML allows for an easy use. However, its limited expressiveness can be an obstacle to the implementation of advanced functions or information formatting. As a result some software tend to extend or modify the format on an non standard way or produce badly formatted output file (which can be reused in other software but do not validate against the official OPML schema).

This has been a problem during our development as following closely he standard may not be enough to support any OPML-compatible software.

For these reasons, some individuals tend to think that the use of OPML as a data interchange format is a bad idea.

Finally, some node metadata available in the official OPML schema are undocumented or implementation-defined. These are remains of the time where OPML served as file format for one particular software but it undermine in our opinion its credibility as a standard document format for outliners.