When you add a Business Data Catalog (BDC) column to a custom list, in the list view column headings you will see an icon with two green circular arrows next to the BDC column - it looks a little like the symbol for a hurricane. This is the "BDC Update" (or "refresh" button). You need to be very careful with this button. When you click this button, it updates the BDC values in your list with the latest values from the BDC for every list item . Why is this necessary? When you use a BDC column in a list, the BDC-related values that you pull in along with the BDC value you enter are actually stored in the list and are not "live" values from the BDC. They are stored at the time you save the list item (create or update). So these values can become "stale" if they change in the database behind the BDC entity. For example, Let's say I add a BDC value "Vendor" to my list for vendors from my back end ERP system. I also pull in the vendor's name, address, and phone number. I add a list item and select a vendor from the BDC. It brings along the vendor's name, address, and phone number and copies of these values get stored in the list. A month later, the vendor's phone number is changed in the ERP system. However, that list item will still show the old phone number, even though the BDC is pulling data directly from the ERP system. It will not automatically update existing list items with the new value (but new list items will...