 Type V ("a"=1, "n"(1)=0, "n"(2)=0) is the interval (0,1] along the axis "a" and type IV ("a"=1, "n"(1)=1, "n"(2)=0) is the vertical open face between the first and fourth quadrants of the "a" = 0 plane with the latter giving the class A limit of each type.In their 1970 work, BKL stated that "as one approaches a singularity, terms containing time derivatives in Einstein's equations dominate over those containing spatial derivatives".This has since been known as the BKL conjecture and implies that Einstein's [[partial differential equations]] (PDE) are well approximated by [[ordinary differential equations]] (ODEs), whence the dynamics of general relativity effectively become local and oscillatory.