The product Mash takes all the information available within Actinic and puts this into the correct format for Amazon. Actinic does not contain all the information that Amazon needs. For example, the ASIN. You can also provide more detailed information to Amazon (e.g. item size), but are not required to list your product.

The additional required information varies depending upon which category it will be listed in (e.g. Home and Garden). In general you should provide 2 additional pieces of information for each of your Actinic products (using Custom Variables), ASIN (or EAN/ISBN) and Manufacturer/Brand. This information can also be useful for other feed types (and improve your searched for products), e.g. Googlebase (Google Shopping).

Unless you have created your products using the ASIN as your Actinic Product ID you will have to add additional information to each product that contains this information.
There is an article on how to do this at the following link:

http://moleend.helpserve.com/Knowledgebase/Article/View/46/0/product-mash-how-to-add-barcodes-eangtin-to-amazon-feed

People normally add various custom values that appear on the same tabs as the other product details. These are then filled in at the same time as the other product details (e.g. Title) when creating products.

To add the Amazon manufacturers value you can use the above approach (using custom values) or if you have defined your product sections with the same text as Amazon (or parent sections) you can use the !!SectionTitle!! macros as the value for this feed setting. More information on these (and other) macros at the following link:

http://www.mole-end.biz/acatalog/PMFAAdvancedInfo.html