_Sidebar.md

@@ -9,6 +9,18 @@ OFMX 0.1.0 (unreleased)
 [AICM 4.5](https://openflightmaps.github.io/ofmx/aixm/4.5/manual/aicm/)<br>
 
 ### Legend
+:bomb: breaking changes<br>
+:warning: important<br>
+:construction: work in progress<br>
+<br>
+&emsp14;↖︎↘︎&emsp13; [association](../Associations#plain-associations)<br>
+&emsp13;⦾&emsp13; [nested](../Associations#nested-associations)<br>
+<br>
+![[M]](https://openflightmaps.github.io/ofmx/svg/m.svg) mandatory<br>
+![[E]](https://openflightmaps.github.io/ofmx/svg/e.svg) mandatory for [OFM Editor](Glossary#ofm-editor)<br>
+![[MD]](https://openflightmaps.github.io/ofmx/svg/md.svg) [[Markdown]] allowed<br>
+![[X]](https://openflightmaps.github.io/ofmx/svg/x.svg) not part of AIXM 4.5
+
 <table>
 <tr><td>:bomb:</td><td>breaking changes</td></tr>
 <tr><td>:warning:</td><td>important</td></tr>