"The L12 (2**11) is a specially designed array, in that interactions are distributed more or less uniformly to all columns. Note that there is no linear graph for this array. It should not be used to analyze interactions. The advantage of this design is its capability to investigate 11 main effects, making it a highly recommended array."
G. Taguchi and S. Konishi (1987). Orthogonal Arrays and Linear Graphs. ASI Press.