These extension methods exist for CQLinq friendly syntax reasons and can only be called in a ICQLinqExecutionContext. Indeed they all rely on a hidden NDepend.TechnicalDebt.IDebtFormatter object, hidden in CQLinq queries. This results in less syntax burden. At CQLinq compilation time, the CQLinq compiler takes care of transforming calls to these extension methods into calls to the proper NDepend.TechnicalDebt.IDebtFormatter object.