Dear all, I am currently developing a tool that outputs an arbitrary number of files, using collections as described in the excellent tutorial by Steve Cassidy at https://web.science.mq.edu.au/~cassidy/2015/10/21/galaxy-tool-generating-dat... . I am having a hard time figuring out how to make galaxy aware of the format of the individual files in the collection, as the two relevant admin help pages I found do not mention this ( https://wiki.galaxyproject.org/Admin/Tools/ToolConfigSyntax and https://wiki.galaxyproject.org/Admin/Tools/Multiple%20Output%20Files). I tried adding a format attribute to the collection tag in the tool description, similarly to ``normal'' single data outputs: <outputs> <collection type="list" format="foo"> <discover_datasets pattern="(?P<name>.*)" directory="bar" /> </collection> </outputs> ... but to no avail. I would be grateful for any helpful pointers! :) Best, Emanuele Lapponi