Hi All, I am a bit lost here. In my xml I have the following sections: <inputs> <param type="data" format="tabular" name="amplitudes" label="amplitude file"/> <param name="samples" type="select" refresh_on_change="true" display="checkboxes" multiple="true" label="Mark quality control samples" dynamic_options='get_column_names(amplitudes)'/> </inputs> <code file="dynamic_options.py" /> In my dynamic_options.py script, I want to parse the headers from 'amplitudes' file and show them in the checkboxes section. My problem seems to be the following. In python, amplitudes is a galaxy object: <galaxy.model.HistoryDatasetAssociation object at 0x7f4fc020a210> How do I parse/access this file to get the headers? It seems to be partly the same problem as asked last week in this conversation: http://dev.list.galaxyproject.org/Question-about-using-dynamic-options-and-r... Thanks! Linda -- Linda Bakker Bioinformatics Research Assistant Plant Research International, Wageningen UR Building 107 (Radix), room W1.Fa.054 Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands tel: +31-317-480756 email: linda.bakker@wur.nl