Noting the primary characteristic previous definitions of grey literature as being an economic perspective on grey literature, the Twelfth International Conference on Grey Literature  added a key curational aspect to existing definitions identifying that ‘Grey literature stands for manifold document types produced on all levels of government, academics, business and industry in print and electronic formats that are protected by intellectual property rights, of sufficient quality to be collected and preserved by library holdings or institutional repositories, but not controlled by commercial publishers i.e., where publishing is not the primary activity of the producing body.’