Author: Lynn Foster <email@example.com>
Date: Sun, 13 Jan 2019 14:51:25 -0600
starting documentation of traversing value flows (#391)
starting documentation of traversing value flows
2 files changed, 27 insertions(+), 2 deletions(-)
diff --git a/docs/appendix/track.md b/docs/appendix/track.md
@@ -12,4 +12,24 @@
> When you "track" a cellphone, you monitor [the starting] location ... and follow it wherever it goes...
-One of the most-often used traces is to find the origins of health problems like mad cow disease and tainted drugs and food. In Value Flows terms, that would start with the product that caused a health problem, and tracing back along the chain of resource flows to the source or sources of the product.-
\ No newline at end of file
+One of the most-often used traces is to find the origins of health problems like mad cow disease and tainted drugs and food. In Value Flows terms, that would start with the product (economic resource) that caused a health problem, and trace back along the chain of resource flows to the source or sources of the product. Then it might be necessary to also track forwards from the source(s) to find everything else that might include that source(s).
+Here is the logic for tracking and tracing.
+* For an EconomicResource:
+ * after: EconomicEvents affecting it that are inputs to Processes or Transfers
+ * before: EconomicEvents affecting it that are outputs from Processes or Transfers
+* For a Process or Transfer:
+ * after: EconomicEvents that are outputs
+ * before: EconomicEvents that are inputs
+* For an EconomicEvent:
+ * after:
+ * a Process or Transfer to which it is an input, or
+ * an EconomicResource which it affected as the output of a Process or Transfer
+ * before:
+ * a Process or Transfer from which is is an output, or
+ * if it is an input to a Process or Transfer, the EconomicResource which it affects.
+When there is more than one economic resource going from input to output of a process without transformation of that resource (except for location), the tracking identifier is used. And example of this would be partial load shipments, where many separate shipments are included in the same shipment process.
+When the same economic resource is both input and output of a process, sometimes a series of processes, such as for repair or quality testing or a workflow where a resource is refined through stages like writing/editing/etc, the stage must be identified, based on the kind of process the resource was last output of.
diff --git a/docs/introduction/concepts.md b/docs/introduction/concepts.md
@@ -31,3 +31,9 @@ Producing and exchange olive oil and coffee, even more simplified.
### ... to thinking bigger.
+### Traversing value flows
+Value flows can be traversed forwards ("tracking") or backwards ("tracing"). Often people use the term "provenance" when looking backwards towards the source of some resource, sometimes when a problem emerges (as in a disease outbreak from food), sometimes to know the quality of the resource (as in wanting local humanely produced food with lower ecological impact).
+The data structures of ValueFlows provide the ability to trace or track any value flow, no matter how long or complex, see [Track and Trace](appendix/track.md).