BookHound 8 standard export files are tab delimted with a .txt extenstion. They are saved in the my_images folder within the BookHound 8 folder.

sku
author
title
subtitle
place_pub
publisher
date_pub
edition
isbn
description
binding
condition
jacket_cond
comments
dj   (y/n)
signed   (y/n)
first_ed   (y/n)
illustrator
keywords
subject 1
subject 2
subject 3
subject 4
subject 5
alt_1
alt_2
alt_3 / type    (later BH8 versions converted alt_3 to type)  
* image_url    (BookHound 8 populates the image_url field with comma separated image URLs)
price
quantity   (0 = delete; > 0 = add)