Add notes for preferred flows and clarify use of Secondarycontextmemb…

…ership

format specs/FlowList.md

@@ -11,8 +11,11 @@ A Flow List is in the form of a pandas data frame with the following fields.
  Unit | string | Y  | The reference unit. uses [olca-ipc.py](https://github.com/GreenDelta/olca-ipc.py) units |
  Class | string | Y | The flow class, e.g. `Energy` or `Chemical` |
  External Reference | string | N | E.g. a web link |
- Preferred | int |  N |   `1` for preferred, `0` for non-preferred
+ Preferred | int |  N |   `1` for preferred*, `0` for non-preferred
  Context | string | Y | A path-like set of context compartments in the form of directionality/environmental media/environmental compartment... e.g. `emission/air/tropophere`|  
  Flow UUID | string | Y | Unique hexadecimal ID for the flow |
  AltUnit | string | N | Alternate unit for the flow |
  AltUnitConversionFactor | float | N | Conversion factor in the form of alternate units/reference unit | 
+
+\* See the [EPA Report](https://cfpub.epa.gov/si/si_public_search_results.cfm?simpleSearch=0&showCriteria=2&searchAll=elementary+flows&TIMSType=Published+Report&dateBeginPublishedPresented=07%2F31%2F2019)
+ for discussion of preferred flows.

format specs/Flowables.md

@@ -10,4 +10,7 @@ Flowable input files are the form of CSV data with the following fields.
  Synonyms | string | N | Flow synonyms |
  Unit | string | Y  | The reference unit. Uses [olca-ipc.py](https://github.com/GreenDelta/olca-ipc.py) units |
  External Reference | string | N | Description or link to definition of flowable |
- Flowable Preferred | int | Y | Indicates whether or not flowable is preferred. `1` for preferred, `0` for non-preferred |
+ Flowable Preferred | int | Y | Indicates whether or not flowable is preferred.* `1` for preferred, `0` for non-preferred |
+
+\* See the [EPA Report](https://cfpub.epa.gov/si/si_public_search_results.cfm?simpleSearch=0&showCriteria=2&searchAll=elementary+flows&TIMSType=Published+Report&dateBeginPublishedPresented=07%2F31%2F2019)
+ for discussion of preferred flowables.

format specs/SecondaryContextMembership.md

@@ -1,6 +1,10 @@
 ## Secondary Context Membership Input File Format
 
-The secondary context membership input file is in the form of CSV data with the following fields. 
+The secondary context membership input file is in the form of CSV data with the following fields.
+Secondary context membership indicates whether or not secondary contexts (see [Contexts](Contexts.md)
+for class definitions) should be associated with flows from this FlowClass with listed primary contexts
+ (Directionality and Environmental Media).
+
 
  Field | Type | Required |  Note |
 ----------- |  ---- | ---------| -----  |
@@ -15,7 +19,7 @@ The secondary context membership input file is in the form of CSV data with the
  Indoor | int |  Y |  `1` for included and `0` for excluded. See note. |
  Population Density | int | Y | `1` for included and `0` for excluded. See note. |  
  Release Height | int | Y | `1` for included and `0` for excluded. See note. |
- ContextPreferred | int | Y | `1` for included and `0` for excluded. See note. |
+ ContextPreferred* | int | Y | `1` for included and `0` for excluded. See note. |
 
-Note: Indicates whether or not contexts with compartment of this class (see [Contexts](Contexts.md) for class definitions)
- should be associated with flows from this FlowClass and primary contexts (Directionality and Environmental Media). 
+ \* See the [EPA Report]((https://cfpub.epa.gov/si/si_public_search_results.cfm?simpleSearch=0&showCriteria=2&searchAll=elementary+flows&TIMSType=Published+Report&dateBeginPublishedPresented=07%2F31%2F2019))
+  for discussion of preferred secondary contexts.