oai-pmh.md

@@ -149,6 +149,14 @@ The mapping used:
 ## Changes in future Release:
 - no Media Type mapping, use of mime/type as is
 - open for spdx.org/license listet except commercial one
+### spdx 
+With oerhub version 1.3 and above we introduce Software Package Data Exchange (spdx).
+```xml
+<lom:description>
+  <lom:langstring xml:lang="x-t-cc-url">https://spdx.org/licenses/Apache-2.0</lom:langstring>
+</lom:description>
+```
+This uri is expected: `https://spdx.org/licenses/<Identifier>`. <Identifier> is the Short Identifier. The link shows the remarks of the license.   
 
 ## Links
 - https://www.openarchives.org/
@@ -163,5 +171,6 @@ The mapping used:
 - https://www.data.gv.at/katalog/dataset/stat_ofos-2012
 - https://www.doi.org/
 - https://creativecommons.org/
+- https://spdx.org/licenses/
 - https://www.openeducation.at/
 - https://oerhub.at/
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