Where two groups of employees, one predominantly female, the other male, perform for the most part identical work, different training and qualifications may result in the two groups using different knowledge and skills acquired through their different disciplines to carry out their job. As a result, they may not be employed to do the same work within Art 141—Angestelltenbetriebstrat der Wiener Gebietskrankenkasse v Wiener Gebietskrankenkasse (1999).