Attribute mappings are created by selecting the source attribute on the datastore entity, dragging it across the workspace and dropping it onto the target attribute on the evidence entity. When the drag is initiated, a representation of the attribute trails the cursor to indicate that it has been "picked up". When the cursor moves out of the datastore entity and into the workspace, a mapping line extends from the entity to the cursor. When the cursor is moved into the evidence entity and placed over the evidence entity attributes, attributes to which a valid mapping can be created turn orange. The user can only create mappings to entity attributes that are highlighted in orange when the cursor is passed over them. If a mapping cannot be created then the attribute the cursor is over will not change color. For further details on invalid mappings see section 3.2 below.