Decompositions of Edge-Colored Digraphs: A New Technique in the   Construction of Constant-Weight Codes and Related Families
  We demonstrate that certain Johnson-type bounds are asymptotically exact for a variety of classes of codes, namely, constant-composition codes, nonbinary constant-weight codes and multiply constant-weight codes. This was achieved via an interesting application of the theory of decomposition of edge-colored digraphs. 
Yeow Meng Chee, Fei Gao, Han Mao Kiah, Alan Chi Hung Ling, Hui Zhang,   Xiande Zhang
math.CO