oai-pmh.md

@@ -66,6 +66,49 @@ For the element langstring the attribute xml:lang is used.
 ```
 > Hint: The repository has to ensure that the language code corresponds to the text of the element!
 
+## FQDN
+oerhub.at usees the FQDN as identifier and catalog
+
+### identifier in _header_-Element
+
+```xml
+<header>
+  <identifier>oai:<$FQDN>:<$ObjID></identifier>
+  <datestamp>2023-02-10T13:34:53Z</datestamp>
+</header>
+```
+example:
+```xml
+<header>
+  <identifier>oai:gecko.aau.at:452</identifier>
+  <datestamp>2023-02-10T13:34:53Z</datestamp>
+</header>
+
+## catalog
+```xml
+<lom:general>
+  <lom:identifier>
+    <lom:catalog><gecko.aau.at><$FQDN></lom:catalog>
+    <lom:entry>
+      <lom:langstring xml:lang="x-none"><$ObjID></lom:langstring>
+    </lom:entry>
+  </lom:identifier>
+  ...
+</lom:general>
+````
+Example:
+```xml
+<lom:general>
+  <lom:identifier>
+    <lom:catalog>gecko.aau.at</lom:catalog>
+    <lom:entry>
+      <lom:langstring xml:lang="x-none">452</lom:langstring>
+    </lom:entry>
+  </lom:identifier>
+  ...
+</lom:general>
+````
+
 ## Vocabs
 ### Creativ Commons
 ```xml