中文摘要：

研究具有混合长度的删位纠错码的存在性问题。利用有向平衡设计，证明了当v≥4时，v｛8，9｝和可能的v≠14，T（2，｛4，5，6｝，v）-码都存在，且给出了码字总数的一个上界。

英文摘要：

Deletion-correcting codes of mixed length are considered.By applying directed pairwise bal-anced design,it is proved that for all positive integers v,v≥4 and v{8,9}and possibly v≠1 4 ,there exists T（2,{4,5,6},v）-codes.The bound of T（2,{4,5,6},v）-codes is also investigated.