Cross-referencing to a page number
There is no specific mechanism for cross-referencing a page number, because DITA is a source format and page numbers are output-dependent. In page layout outputs, a cross-reference to an element in a topic will be automatically generated as a page reference.
When you cross-reference to a topic, or to an element within a topic, and then publish to a page layout format such as PDF, the publishing processor will typically calculate the page number of the referenced topic or element.
For example, a cross-reference to a figure will typically be rendered, when published to PDF, as: Figure 1: Title of Figure (see page number).
DITA is designed around the concept of the separation of content and form. Page numbers are part of the form, and are therefore always generated as part of the publishing process that converts the DITA source to a reading format output.
Avoid cross-referencing simple paragraphs or other points in a topic in order to generate a page number reference. Cross-references should be to the topic as a whole.