This little bit is all you need. You specify the name, which is the name you gave to the column already. The entity is the name the table will get when it is stored in the database. The dataType is, as you might have guessed, the type of data that is present in each column. The description column allows you to describe your attribute. If you want to have a value point to another table, you can use the refEntity column. Complex data structures do not always consist of a single table, we support multiple table models through this system of reference entities. The idAttribute parameter will tell MOLGENIS that this is the primary key. It has to be unique, and it is not allowed to be null or missing. With the nillable parameter you can enforce whether an attribute is allowed to be missing or not.