Explanation
===========

Narrative material on *why* ``pgp-pcie-apps`` is structured the way it
is — the layered protocol decomposition, the data-flow conventions, the
relationship with ``axi-pcie-core`` and ``surf``.

.. toctree::
   :maxdepth: 2
   :caption: Explanation

   architecture
   data_flow
   protocol_variants
   clock_domains
   relation_to_axi_pcie_core