### Axis steps

The basic primitive for accessing a source document is the axis step. Axis steps may be combined into path expressions using the path operators "/" and "//", and they may be filtered using filter expressions in the same way as the result of any other expression.

An axis step has the basic form axis::node-test, and selects nodes on a given axis that satisfy the node-test. The axes available are:

1. element: age

2. element: age

The rest of the axes act in the same manner.