-FIXME describe how `pazpar2_url` is assembled from `pp2_hostname` and `pp2_path`; and how `service_proxy_auth` is assembled from
-`auth_hostname` or `pp2_hostname`, `sp_auth_path`, `sp_auth_query` and `sp_auth_credentials`.
+Most of MKWS's functionality is achieved by use of the Pazpar2 middleware. This is accessed on an endpoint URL which is usually
+assembled from the two configuration sessings `pp2_hostname` and `pp2_path`. However, if for some reason an unusual Pazpar2
+endpoint must be used, that endpoint can be specified in the `pazpar2_url` setting, and that will be used instead.
+
+In the common case where Pazpar2 is accessed via the Service Proxy, an authentication call is made during initialisation. The call
+is generally made to the same endpoint as the other requests. However,
+
+and how `service_proxy_auth` is assembled from
+`sp_auth_hostname` or `pp2_hostname`, `pp2_path` or `sp_auth_path`, `sp_auth_query` and `sp_auth_credentials`.