[galaxy-dev] Tabular file metadata - columns names

Hi all, I'd like to know more about Galaxy's column metadata for tabular files. In the workflow editor under "Edit Step Actions" you can pick "Assign Columns", and then give column numbers for five predefined cases: Chrom, Start, End, Strand, Name. Do these "named columns" get shown anywhere in the Galaxy UI? For example, in a column select parameter widget? Is it possible to assign these columns in a tool's wrapper XML file? I'm aware of the metadata_source attribute to *copy* the meta data from the input file, but that isn't always relevant. Can I somehow specify that my tool has tabular output where column 1 is "Name"? Is it possible to introduce additional column types? e.g. "evalue" or "Description". Thanks, Peter