Associations.md

-Related features are associated by the use of `*Uid` tags. Take this example:
+Related features are associated by the use of `*Uid` tags.
+
+## Plain Association
+A VOR-DME is a good example. This [[navigational aid]] is a combination of a VOR and a DME.
 
 ```xml
 <Vor>
@@ -24,11 +27,40 @@ Related features are associated by the use of `*Uid` tags. Take this example:
 </Dme>
 ```
 
-This navigational aid is a VOR-DME, an integrated combination of a VOR and a DME.
+The `VorUid` [[uniquely identifies|identification]] this `Vor` feature. The `Dme` feature contains the full `VorUid` which associates it to the `Vor`.
+
+The bonding between the two features is weak: Say, if the `codeId` of the `Vor` changes, the `DmeUid` does *not* automatically change as well. 
+
+## Nested Association
+The association may be nested inside another `*Uid` tag such as [[airports|airport]] and their runways do:
+
+```xml
+<Ahp>
+  <AhpUid>
+    <codeId>LFNT</codeId>
+  </AhpUid>
+  (...)
+</Ahp>
+<Rwy>
+  <RwyUid>
+    <AhpUid>
+      <codeId>LFNT</codeId>
+    </AhpUid>
+    <txtDesig>16R/34L</txtDesig>
+  </RwyUid>
+  (...)
+</Rwy>
+```
+
+The `AhpUid` [[uniquely identifies|identification]] this `Ahp` feature. The `Rwy` feature contains the full `AhpUid` inside it's `RwyUid` which associates it to the `Ahp`.
+
+The bonding between the two features is strong: Say, if the `codeId` of the `Ahp` changes, the `RwyUid` does automatically change as well. 
+
+## mid
 
-The `VorUid` [[uniquely identifies|identification]] this `Vor` feature by it's code and position. The `Dme` feature contains the full `VorUid` which associates it to the `Vor`.
+Since a `*Uid` tag may contain quite a number of key properties, the recognition of identical `*Uid` tags in order to associate features is a cumbersome task sometimes.
 
-In the above example, the `VorUid` is rather complex and contains three properties. To facilitate the recognition of such associations, you may add an `mid` attribute:
+To facilitate this matching, you can add an `mid` attribute to the `*Uid` tag:
 
 ```xml
 <Vor>
@@ -54,4 +86,4 @@ In the above example, the `VorUid` is rather complex and contains three properti
 </Dme>
 ```
 
-:warning: Even if a `mid` attribute is present, the properties wrapped by the `*Uid` tag must not be omitted.
+:warning: Even if a `mid` attribute is present, the key properties wrapped by the `*Uid` tag must not be omitted.
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