If there is data in the CustomFields field, it pulls the Value part of the Key-value pair in the product feed into the description template, and displays that data in the listing.
When MIP processes a Distribution or Product-combined feed and finds a description template name in the TemplateName field, it uses the description template instead of the standard eBay description file to display the listing. Description templates are generally created by experienced eBay sellers who want custom layouts for their products or store, or for a specific listing.
They contain layout, font, and color information, and can use CSS files to define the parameters.
Description templates are optional user-created HTML files that set up the look and feel of product listings on the eBay site.
