Hi, my tool needs both a file with chromosome lengths and the total mappable genome size. I would like to hardcode the mappable genome size per build somewhere. However the user should have to use only one drop down to select both. How can I achieve this? e.g. currently: <param name="FAI" type="select" label="Select chromsome sizes" > <options from_file="chrsize.loc"> <column name="name" index="0"/> <column name="value" index="1"/> </options> </param> with chrsize.loc: mm9 /groups/csf-ngs/wfsys/galaxy/tool-data/shared/ucsc/chrom/mm9.len mm10 /groups/csf-ngs/wfsys/galaxy/tool-data/shared/ucsc/chrom/mm10.len hg19 /groups/csf-ngs/wfsys/galaxy/tool-data/shared/ucsc/chrom/hg19.len dm3 /groups/csf-ngs/wfsys/galaxy/tool-data/shared/ucsc/chrom/dm3.len Currently I multiply the genome size from the fai file by 0.8 to get the mappable size within my tool, but I would like to use more exact numbers per build. thank you very much, ido