diff --git a/Licenses/README b/Licenses/README
index 9f61192557..c6ff2774fc 100644
--- a/Licenses/README
+++ b/Licenses/README
@@ -37,6 +37,18 @@ replaced by a single line:
 
 	SPDX-License-Identifier:	GPL-2.0+
 
+Ideally, the license terms of all files in the source tree should be
+defined by such License Identifiers; in no case a file can contain
+more than one such License Identifier list.
+
+If a "SPDX-License-Identifier:" line references more than one Unique
+License Identifier, then this means that the respective file can be
+used under the terms of either of these licenses, i. e. with
+
+	SPDX-License-Identifier:	GPL-2.0+	BSD-3-Clause
+
+you can chose between GPL-2.0+ and BSD-3-Clause licensing.
+
 We use the SPDX Unique License Identifiers here; these are available
 at [2].