Facebook catalog feeds are CSV files, containting the following comma-seperated values, as required by the Facebook Catalog feed specifications:

• id - a unique identifier for your listing. Format: <your shop id>.<listing id>
• item_group_id - group ID for all the variations of this listing.
• size - item size if applicable. 'N/A' if not available.
• age_group - the age group that the item is targeted towards.
• title - Etsy listing title (limited to 65 characters).
• description - Etsy listing description. [unless you chose to use the listing title, in the 'Settings' tab]
• availability - fixed value: 'in stock'.
• condition - according to your selection in the drop-down menu above.
• link - a link to your Etsy listing.
• price - Etsy listing price (prior to discounting, if a sale is defined).
• sale price - Etsy discounted listing price, if a sale is defined. Otherwise, same as price
• image_link - a link to your Etsy listing main image.
• additional_image_link - links to up to 3 additional images of your item, separated by a vertical bar (|)
• brand - your shop name as it appears on Etsy.
• google_product_category - according to your setting in the 'Settings' tab.
• gender - your target audience as indicated in General Settings above.
• quantity_to_sell_on_facebook - your target audience as indicated in General Settings above.
• custom_label_0 - will contain a list of all the listing tags that can fit into 100 characters (a Facebook restriction).
• custom_label_1 - will contain the shop section name for this item.