Location steps

    axis :: node-test [ predicate ]

• The axis selects a set of candidate nodes (e.g. the child nodes of the context node).

• The node-test performs an initial filtration of the candidates based on their
  • types (chardata node, processing instruction, etc.), or
  • names (e.g. element name).

• The predicates (zero or more) cause a further, potentially more complex, filtration.
  Only candidates for which the predicates evaluate to true are kept.

This structure of location paths and steps makes implementation rather easy.

The example from before:

child::section[position()<6]/descendant::cite/attribute::href

selects all href attributes in cite elements in the first 5 sections of an article.