Format
The format is:
int [1:200, 1:20] 3 2 2 3 3 3 2 3 3 3 ...
- attr(*, "dimnames")=List of 2
..$ : chr [1:200] "D1M1" "D1M2" "D1M3" "D1M4" ...
..$ : NULLSource
Broman,K., et al. (2003) R/qtl: QTL mapping in experimental crosses, Bioinformatics, 19, 889-890.