note site vs flow replacement

volumes/ecocounter/readme.md

@@ -157,7 +157,7 @@ When you want to update new rows with missing `centreline_id`s, use [this script
 | geom | geometry |  | |
 | facility_description | text | | description of bike-specific infrastructure which the sensor is installed within |
 | notes | text | | |
-| replaced_by_site_id  | numeric | | Several sites had their sensors replaced and show up now as "new" sites though we should ideally treat the data as continuous with the replaced site. This field indicates the site_id of the new replacement site, if any. |
+| replaced_by_site_id  | numeric | | Several sites had their sensors replaced and show up now as "new" sites. This field indicates the site_id of the new replacement site, if any. Please note that any attempt to combine counts from one site with those of its replacement should be done at the level of flows. |
 | centreline_id | integer | | The nearest street centreline_id, noting that ecocounter sensors are only configured to count bike like objects on a portion of the roadway ie. cycletrack or multi-use-path. Join using `JOIN gis_core.centreline_latest USING (centreline_id)`. |
 | first_active | timestamp without time zone | | First timestamp site_id appears in ecocounter.counts_unfiltered. Updated using trigger with each insert on ecocounter.counts_unfiltered. |
 | last_active | timestamp without time zone | | Last timestamp site_id appears in ecocounter.counts_unfiltered. Updated using trigger with each insert on ecocounter.counts_unfiltered. |