datasets.md

 # Datasets
 
-Datasets are the cornerstone of the CC. 
+In the CC nomenclature, a dataset is determined by:
+
+1. One coordinate.
+2. One (typically) or multiple (eventually) sources having the same type of (mergeable) data.
+3. A processing procedure yielding signatures type 0.
 
 ## Levels, coordinates and datasets
 
@@ -44,7 +48,7 @@ In turn, each level is divided in 5 sublevels or **coordinates** representing di
 |`E4`|Disease phenotypes|Manually curated relationships between chemicals and diseases. Chemicals include drug molecules and environmental substances, among others.|
 |`E5`|Drug-drug interactions|Changes in the effect of a drug when it is taken together with a second drug. Drug-drug interactions may alter pharmacokinetics and/or cause side effects.|
 
-Each of the coordinates can contain an arbitrary number of **datasets**. All datasets are fully described in the [PostGreSQL database](database), and searchable at `http://chemicalchecker.org/datasets/`. They receive a numbered coding (e.g. `A1.001`).
+Each of the coordinates can contain an arbitrary number of **datasets**. All datasets are fully described in the [PostGreSQL database](database), and searchable at the [CC web app](http://chemicalchecker.org/datasets/) (:warning: not done yet). They receive a numbered coding (e.g. `A1.001`).
 
 ## Dataset characteristics