[ic] OK to remove columns in products.xls?

[Hostmaster]

Hello list members,
I've used the products.xls example supplied with IC to build a product
database for my client which contains 1891 records.  There are some fields
on the spreadsheet that I can't place on the catalog.  Can someone tell me
what the following fields are for, and where on the catalog they are found?
1)  title  (we are using description and comments, but this field eludes
us - where would we see it on the demo?)
2)  related
3)  dl_type
4)  dl_location
5)  inactive
6)  image_large  (I see where thumb and image are used, but not image_large)

If we don't need certain fields in our catalog, is it safe to remove them,
or does Interchange require the fields be included, whether they are used or
not?

Thank you,
Michael G.