Edit section "Extension Steps"

[xml-project]

The first sentence of section "Extension step" currently is:

Pipeline authors may also have access to additional steps not defined or described by this specification. Atomic extension steps are invoked just like standard steps ...

I wonder if it makes sense to be a bit more elaborate here because this section not only applies to the minor case of build-in processor extensions but also to the IMHO much larger use case of calling steps declared by pipeline authors with p:declare-step.

[ndw]

Sure. Go ahead and propose something more complete.

[xml-project]

Will do!

[gimsieke]

Also consider the comments in #635 about regrouping the current “atomic steps” and “extension steps” sections and adapting the prose in Sect. 17.5. In 17.5, there is currently a distinction between “atomic steps” (in the sense of processor-implemented standard steps) and “pipelines” (user-defined steps written in XProc). The distinction should follow the proposed new distinction in 16.8.

Proposal for regrouping 16.8 and 16.9. (thereby eliminating 16.9):

16.8 Atomic Steps
16.8.1 Processor-Implemented Standard Atomic Steps
All atomic steps whose type is in the XProc namespace and whose declarations don’t have a subpipeline

16.8.2 Standard Atomic Steps Written in XProc
There aren’t any yet. This section will only be included if we decide to pursue this way.

16.8.3 User-Defined Atomic Extension Steps
Declaration with subpipeline, namespace not XProc, need to be imported.

16.8.4 Atomic Processor Extension Steps
Declaration without subpipeline, namespace not XProc. Whether they need to be imported (or which need not be imported, like the EXProc steps in 1.0 for certain processor versions, I believe) is implementation-defined.

16.8.5 Atomic Step Errors
XS0010, XS0044, XS0048, XD0010

[ndw]

Clarify: steps in the XProc namespace do not have to be imported, everything else does.