For its work on the SE, the ETUI‘s SEEurope network has distinguished between different types of SE so as to better describe the diversity of SEs which quickly evolved after October 2004. The categorisation allows distinction between SEs depending on whether the company has operations and employees (‘normal SE’), operation but no or very few (≤ 5) employees (‘micro /empty SE’). SEs which are probably operating but where there is not enough information for classification (e.g. on employees) are referred to as ‘UFO SEs’ (‘Unidentified Flying Objects’). This group also contains so-called shelf or shell SEs which were set up without any operations or employees.

From an employee involvement perspective, the main focus of interest is the ‘normal SEs’. However, collection of information on empty/micro and UFO SEs is crucial to be able to follow up if they are subsequently acquire employees.