Update 05-implementation.md

documentation/design/05-implementation.md

@@ -35,7 +35,8 @@ There seem to be two classes of information to be stored in the controller:
 * short-living information, such as, current configured network flows or obtained network configuration out of use case #1 (CoCSN)
 * long-time information, such as, information about principle network domains, elements in such a domain if directly learned from SBI, etc 
 
-This may or may not result in two different places to store data. Unclear yet. 
+Long-time information should be persistenly stored in the database and survive reboots of goSDN etc. Short-Living information doesn't have to survive reboots of goSDN
+
 
 ### Some more details for implementation for the database(s)
 
@@ -45,4 +46,6 @@ Specification of a PND:
 * Human readable name of PND
 * Textual description for further information
 * Set of supported Southbound-Interfaces, e.g., RESTCONF, TAPI, OpenFlow etc
-* Phyiscal Inventory Network Elements, hosts and links 
+* Physical Inventory Network Elements, hosts and links, pontentially only the SBI SDN controller
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+
+A PND entry must be explicitly generated, though some information can be automatically be generated, e.g., the physical inventory for use-case #1 (CoCSN) would mean that the information about the SBI domain specific SDN controller is entered. 
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