swish/commit

Updated RDF prefix handling example

diff --git a/examples/prefix_examples.swinb b/examples/prefix_examples.swinb
index b121633..3edf2fc 100644
--- a/examples/prefix_examples.swinb
+++ b/examples/prefix_examples.swinb
@@ -3,10 +3,28 @@
 <div class="nb-cell markdown">
 # Using RDF prefixes
 
-RDF prefixes make long RDF resources readable and consistent renaming of resources.
-They are supported by the Prolog predicates rdf_register_prefix/2, rdf_register_prefix/3 and rdf_current_prefix/2.  In the current version, RDF prefixes are _global_ to the SWI-Prolog instance, i.e., all parts of the program share the same prefix declarations.
+RDF prefixes make long RDF resources readable and allow for consistent renaming of resources.  The RDF interface expands
+terms of the shape Prefix:Local to a full URI, i.e., an _atom_.  The library supports both **global** and **local** prefix
+declarations:
 
-A consequence of this is that prefixes cannot be defined if SWISH operates in anonymous query mode.
+  - **Global** prefix declarations are declared using the Prolog predicates rdf_register_prefix/2 or rdf_register_prefix/3.
+  They should be considered a property of the data and are normally declared with the application.  Global prefixes may also
+  be defined through the ClioPatria interface.  Global prefixes can only be added by priviledged users.
+
+  - **Local** prefixes can de declared using `:- rdf_prefix(Prefix, URI)`.  They are local to a module and take preference
+  over globally defined prefixes.  The rdf_prefix/2 declaration can be used in SWISH programs.  As they are local to the
+  temporary SWISH module there is no interference with other users.
+
+RDF Prefix declarations causes calls to predicates that are declared using rdf_meta/2 as well as the predicate head of such
+predicates to be subject to **prefix expansion**.  In addition, the following predicates can be used to interact with the
+prefix declarations:
+
+  - [[rdf_current_prefix/2]]
+  - [[rdf_global_id/2]]
+  - [[rdf_global_object/2]]
+  - [[rdf_global_term/2]]
+
+## Enumerating the known prefixes
 
 The currently known prefixes are easily enumerated:
 </div>
@@ -58,19 +76,19 @@ person(P).
 <div class="nb-cell markdown">
 Something similar to the above example happens less obviously in real code.  We discuss these cases below.
 
-### A &lt;prefix&gt;:&lt;local&gt; term is passed to a user defined predicate. 
+### A &lt;prefix&gt;:&lt;local&gt; term is passed to a user defined predicate.
 
 In this case Prolog does not know that the user predicates expects a resource and thus does not expand the resource.  This can be fixed using an rdf_meta/1 declaration as shown in the code below, but unfortunately this is *not yet supported by SWISH*.
-    
+
     ```
     :- rdf_meta
-    	instance_of(r,r).
+	instance_of(r,r).
 
     instance_of(I, Class) :-
-    	rdf(I, rdf:type, Class).
+	rdf(I, rdf:type, Class).
 
     person(P) :-
-    	instance_of(P, foaf:'Person').
+	instance_of(P, foaf:'Person').
     ```
 The work-around is to use rdf_equal/2.  This predicate is defines normal _unification_, but is annotated to expect an RDF resource as argument.  This
 results in the following definition:
@@ -101,4 +119,23 @@ one into the prefix and local name.  Note the rendering of `Resource` as an abbr
 Term = foaf:'Person', rdf_global_id(Term, Resource).
 </div>
 
+<div class="nb-cell markdown">
+## Defining prefixes in SWISH programs
+
+As stated in the beginning of this notebook, **global** prefixes cannot be defined in SWISH programs unless the user is logged on
+with sufficient authorization.  Any program can use **local** prefixes though.  The code below illustrates this.  Local prefix
+declarations take precedence over global ones.
+</div>
+
+<div class="nb-cell program">
+:- rdf_prefix(me, 'http://example.org/me/').
+
+person(X) :-
+    rdf(X, rdf:type, me:'Person').
+</div>
+
+<div class="nb-cell query">
+listing(person/1).
+</div>
+
 </div>