[DOC] Specs to indicate the position of global metrics.

docs/architecture.md

 
-# Global Parameters
+# Definitions and notation for the documentation (!= python notation)
+
+## Node
+
+The table (nodes) is a list of nodes: [Node]
+
+Each Node has:
+- a typename
+- a parent_id
+- a name
+
+
+### Each Node has a parent_id
+
+Node A
+├── Node B
+└── Node C
+
+If Node A is Parent of Node B and Node C
+then NodeA.id == NodeB.parent_id == NodeC.parent_id.
+
+### Each Node has a typename
+
+Notation: Node[foo](bar) is a Node of typename "foo" and with name "bar".
+
+Then:
+    - Then Node[project] is a project.
+    - Then Node[corpus] is a corpus.
+    - Then Node[document] is a document.
+
+
+### Each Node as a typename and a parent
+
+
+Node[user](name)
+├── Node[project](myProject1)
+│   ├── Node[corpus](myCorpus1)
+│   ├── Node[corpus](myCorpus2)
+│   └── Node[corpus](myCorpus3)
+└── Node[project](myProject2)
+
+
+/!\ 3 way to manage rights of the Node:
+    1) Then Node[User] is a folder containing all User projects and corpus and
+documents (i.e. Node[user] is the parent_id of the children).
+    2) Each node as a user_id (mainly used today)
+    3) Right management for the groups (implemented already but not
+    used since not connected to the frontend).
+
+
+## Global Parameters
 
 Global User is Gargantua (Node with typename User).
 This node is the parent of the others Nodes for parameters.
 
-* Global TFIDF
-    - scores saved in NodeNgram
-    - where
-        - Node with typename TFIDF-Global 
-        - Node with with parent_id node with typename Gargantua 
+Node[user](gargantua) (gargantua.id == Node[user].user_id)
+├── Node[TFIDF-Global](global) : without group
+│   ├── Node[tfidf](database1)
+│   ├── Node[tfidf](database2)
+│   └── Node[tfidf](database2)
+└── Node[anotherMetric](global)
+
+
+
+## NodeNgram
+
+NodeNgram is a relation of a Node with a ngram:
+    - document and ngrams
+    - metrics  and ngrams (position of the node metrics indicates the
+      context)
+