For example, to enable visualization of hg18, a file called hg18.len must exist in the previously specified folder. The contents of the .len file is tab-delimited and specifies the length of each chrom/contig of that build, each on a separate line, eg:
chr1 27473282 chr2 38882233 ... chrX 28883322My question is that : where to find the length information for chromosomes of hg18 ?