The focus on these costs in the construction of the indicators reflects the dominant approach taken in the empirical and theoretical literature examining the labour market impact of employment protection discussed in the previous section. It does not reflect the overall strictness of regulation of collective dismissals, which is the sum of costs for individual dismissals and any additional cost of collective dismissals. It concerns the types of work for which these contracts are allowed and their renewal and cumulative duration. This measure also includes some of the regulations governing the establishment and operation of temporary work agencies and requirements for agency workers to receive the same pay and/or working conditions as equivalent workers in the user firm, which can increase the cost of using temporary agency workers relative to hiring workers on other types of contracts.