updating discussion of spatial thing and feature

bp/index.html

@@ -398,7 +398,8 @@ <h2>Spatial Things, Features and Geometry</h2>
         in <span style="background-color:yellow">[W3C-BASIC-GEO]</span> as “Anything with spatial
         extent, i.e. size, shape, or position. e.g. people, places, bowling balls, as well as
         abstract areas like cubes”.</p>
-      <p>The term “<a>spatial thing</a>” is considered equivalent to “<a>feature</a>” in the first sense discussed above. Furthermore, we treat it as equivalent to other commonly used definitions; e.g. <strong>Feature</strong> from <span style="background-color:yellow">[<a href="http://geovocab.org/doc/neogeo/">NeoGeo</a>]</span>, described as “A geographical feature, capable of holding spatial relations”.</p>
+
+      <p>The concept of “<a>spatial thing</a>” is considered to include <em>both</em> "real-world phenomena" <em>and</em> their abstractions (e.g. “<a>feature</a>” as defined in <span style="background-color:yellow">[ISO-19101]</span>). Furthermore, we treat it as inclusive of other commonly used definitions; e.g. <strong>Feature</strong> from <span style="background-color:yellow">[<a href="http://geovocab.org/doc/neogeo/">NeoGeo</a>]</span>, described as “A geographical feature, capable of holding spatial relations”.</p>
       <div class="note">
         <p>A <a>spatial thing</a> may move. We must take care not to oversimplify our concept of <a>spatial thing</a> by assuming that it is equivalent to definitions such as <strong>Location</strong> (from [[DCTERMS]]) or <strong>Place</strong> (from <span style="background-color:yellow">[<a href="http://schema.org">schema.org</a>]</span>), which are respectively described as “A spatial region or named place” and "Entities that have a somewhat fixed, physical extension".</p>
       </div>