The L2Cache is a storage for parameters of individual L2 IDs in the PyChunkedGraph. L2 IDs represent the connected component of the supervoxel graph within a chunk. The most anticipated use of the L2 Cache is to query the information stored for all L2 IDs making up a single neuron. For instance, the volume of a neuron can be computed from the volume of all its L2 IDs.
The main reason to store information for the L2 level is to make computation and retrieval of neuron-level information fast and easy following an edit. Edits typically only affect a few chunks among hundreds or thousands spanned by a neuron. Hence, information only needs to be recomputed for a few chunks instead of all of them.