diff --git a/Rules-for-adding-new-device-types.md b/Rules-for-adding-new-device-types.md
index 8f92f9b..c1aaddf 100644
--- a/Rules-for-adding-new-device-types.md
+++ b/Rules-for-adding-new-device-types.md
@@ -9,4 +9,5 @@ Steps for adding a new device type:
 5. Verify that _rasctl -s_ reports the correct device type properties.
 6. Update the manpages.
 
-Devices should inherit from the PrimaryDevice or ModeSenseDevice classes. Only devices backed by image files should inherit from the Disk class. See the implementation of the Host Services (SCHS) for a device implementation with low complexity.
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+Devices shall be subclasses of PrimaryDevice or ModeSenseDevice. Only devices backed by image files shall be subclasses of the Disk class.
+See the implementations of the Host Services (SCHS) and the SCSI Printer (SCLP for a device implementations with low complexity.
\ No newline at end of file