Updated Concepts (markdown)

Concepts.md

@@ -21,6 +21,17 @@ A part entity have many fields, which can be used to describe it better. Most of
 * **Mass**: The mass of a single piece of this part (so of a single transistor). Given in grams.
 * **Internal Part number** (IPN): Each part is automatically assigned an numerical ID which identifies a part in the database. This ID depends on when a part was created and can not be changed. If you want to assign your own unique identifiers, or sync parts identifiers with the identifiers of another database you can use this field.
 
+### Stock / Part lot
+A part can have many stock at multiple different locations. This is represented by part lots / stocks, which consists basically of a storelocation (so where are the parts of this lot are stored) and an amount (how many parts are there).
+
+### Purchase Informations
+The purchase informations describe where the part can be bought (at which vendors) and to which prices.
+The first part (the order information) describes at which supplier the part can be bought and which is the name of the part under which you can order the part there.
+An order information can contain multiple price informations, which describes the prices for the part at the supplier including bulk discount, etc.
+
+### Parameters
+
+
 ## Core data
 ### Category