Over the years, the planning system has undergone a number of alterations, which were consolidated in the Town and Country Planning Act 1990 (TCPA 1990). Section 106 substantially re-wrote Section 52 from the former Act, settling the concept of agreements (known as "planning obligation agreements," or more commonly "Section 106 agreements"), under which the developer is subject to detailed arrangements and restrictions beyond those that a planning condition could impose, or by which they make agreed financial contributions beyond the immediate building works to offset development effects on the local community. This was soon amended to allow a developer to self-impose obligations to preempt objections to planning permission. This prevents the planning authority from blocking a permission by merely failing to negotiate.