XProc core steps in Componize

Several XProc steps are defined as requirements in the "core" subset the XProc specification. Componize implements core actions like looping, conditional processing, or exception handling.

Declares a pipeline that can be evaluated by the XProc processor. The children declare inputs, outputs, and options that the pipeline exposes and identify the steps in its subpipeline. A p:pipeline is a simplified form of step declaration.
Compound step that processes a sequence of documents, applying its subpipeline to each document in turn.
Multi-container step that selects exactly one of a list of alternative subpipelines based on the evaluation of XPath expressions.
Specifies one subpipeline guarded by a test expression.
Specifies the default branch. The subpipeline selected if no test expression on any preceding p:when evaluates to true.
A group encapsulates the behavior of its subpipeline. In a p:try, a group is a non-step wrapper, everywhere else, it is a compound step.
Specifies a try/catch. It is a multi-container step that isolates a subpipeline, preventing any dynamic errors that arise within it from being exposed to the rest of the pipeline.
Identifies the recovery pipeline of a p:try.
Identifies an input port for a step. In some contexts, p:input declares that a port with the specified name exists and identifies the properties of that port. In other contexts, it provides a connection for a port declared elsewhere. And in some contexts, it does both.
Identifies input to a p:for-each.
Identifies an output port, optionally connecting an input for it, if necessary.
Declares an option and may associate a default value with it. The p:option tag can only be used in a p:declare-step or a p:pipeline (which is a syntactic abbreviation for a step declaration).
Provides an actual value for an option when a step is invoked.
Used to establish the value of a parameter. The parameter must be given a value when it is used.
Provides the type and signature of an atomic step or pipeline. Declares the inputs, outputs, and options for all steps of that type.
A collection of step declarations and/or pipeline definitions.
Loads a pipeline or pipeline library, making it available in the pipeline or library which contains the p:import.
Connects an input to a port on another step.
Reads an XML document from a URI.