... 1[e, f]]]) becomes this bitsequence 000001110110111010111011111100101. Compare these 33 required bits to the 50 bits required for a fixed-length encoding of the tree, using non-NIL coding. Note that =-=[8]-=- already introduced a simple bit coding of SLT grammars. In our experiments we found that a threshold of 14 was optimal on our data set, for the uncompressed and gzipped version of BPLEX output, both ...