Deprecated. This field will be removed from the schema in a future release. Recommended usage as of release 439 varies for eBay.com listings and Half.com listings.
For eBay.com listings: As of release 439, this field can still be passed in, but we recommend that you update your applications to use the ExternalProductID field defined on the item instead (i.e., Item.ExternalProductID). If you specify both Item.ExternalProductID and this field in the same request, eBay uses the value in Item.ExternalProductID and ignores the value in this field. See Item.ExternalProductID for information on using an external ID for eBay.com listings.
For Half.com listings: As of release 439, this field is required for Half.com listings. Causes Half.com to list the item with Pre-filled Item Information based on an ISBN value or other supported external ID, plus other meta-data that you specify. See the eBay Web Services guide for information about listing to Half.com.
See the
Field Index to learn which calls use ExternalProductID.