Step 1: Log in to your AbeBooks account, scroll down to the footer and click on 'Customer Support'.

Copy everything between the green notes and paste / send it to ABE using either Method 1 or 2.
Start copy below...
Please note my new upload file is now coming from BookRouter™ in your standard AbeBooks format per your support documentation here:

Login to Abebooks. Scroll down to the 'Member's Menu' then click 'Account Details' under the 'My Personal Information' heading.
Scroll down to 'Account information'. The 'User ID' is your FTP Username.
Login to your BookRouter's Admin/Control Panel. Click on 'Marketplaces' under the 'Routing' heading.
In the Marketplaces list, locate 'AbeBooks', then click the 'Edit' icon in the 'Actions' column to update its details.
On the right-side panel, leave the 'Routing Status' set to 'Paused' until you receive confirmation that AbeBooks has adjusted your upload format.
Once Abebooks has confirmed that your upload format has been adjusted, update your 'Pricing Strategy' details and 'Sync Rules' preferences and change the following settings:
Routing Status: set to “Enabled”
Purge Ready: set to “Yes” (only do this if your website inventory is up to date)
You can choose from the 'Save' dropdown options in the top-right corner:
a) Save and Exit – Saves your changes and closes the page.
b) Exit without Saving – Leaves the page without saving your changes.
Be sure to select Save and Exit if you want your updates to be applied.