XProc has a lot of built-in steps. Their functionality is described in the specification.
However, this description was aimed at XProc engine developers, not at XProc users/programmers
Hooray! There is now a website with information about the built-in XProc …

With half the globe in lockdown or just out of it, a physical Markup UK conference is not an option. There's nothing stopping a webinar, however, so Markup UK will be offering a series of them throughout June, free of …

We are very pleased to announce the release of MorganaXProc-IIIse 0.9.0-beta.

XProc 3.0 is an XML pipeline language which is developed as a successor to XProc 1.0. Compared to XProc 1.0 is has many new and powerful features such as …