If you are not one already, you would need to sign up as a Professional seller in order to access the Inventory File Templates which will validate your data. I assume you are trying to create new products that don't already exist on Amazon or add/change data on existing products. For this you would need one of the Category Specific Inventory Files. https://www.amazon.com/gp/help/customer/display.html?ie=UTF8&nodeId=200186090
Let's say you're trying to upload a flat file for Books. You would first download the Flat.File.BookLoader template from the above URL. Fill out your data. Fill out your MWS security credentials on the Add-Ins tab. Click the Validate button on the Add-Ins tab. If everything is good, click Upload File, also on the Add-Ins tab.
There's also the Check File feature at the Seller Central website > Inventory > Add Products via Upload > Upload Inventory Files > "Select type of file to upload" > Check File button.
I just saved 1 line of test data from within the template as a tab delimited text file. There's 3 rows of Amazon headers and a LOT of columns. Some columns require data in order to be valid, others do not. Here's what I got:
TemplateType=BookLoader Version=2013.1024 The top 3 rows are for Amazon.com use only. Do not modify or delete the top 3 rows. Offer - These attributes are required to make your item buyable for customers on the site Discovery - These attributes have an effect on how customers can find your product on the site using browse or search Image - These attributes provide links to images for a product Fulfillment - Use these columns to provide fulfillment-related information for either Amazon-fulfilled (FBA) or seller-fulfilled orders. Ungrouped - These attributes create rich product listings for your buyers.
SKU Product ID Product ID Type Title Publisher Product Description Update Delete Author Binding Publication date Edition Number Standard Price Quantity Item Condition Offer Condition Note Product Tax Code Expedited Shipping Will Ship Internationally Standard Plus Scheduled Delivery SKU List Search Terms1 Search Terms2 Search Terms3 Search Terms4 Search Terms5 Main Image URL Main Offer Image Offer Image1 Offer Image2 Offer Image3 Offer Image4 Fulfillment Center ID Package Height Package Width Package Length Package Dimensions Unit Of Measure Package Weight Package Weight Unit Of Measure Subject Language Illustrator Signed By Dust Jacket Condition Pages Number in Series Series Title Editor Preface Colorist Compiler Composer1 Composer2 Composer3 Composer4 Composer5 Composer6 Composer7 Composer8 Composer9 Composer10 Creator Drawings Painter Reader Series Editor Technical editor Adapter Afterword Artist1 Artist2 Artist3 Artist4 Artist5 Artist6 Artist7 Artist8 Artist9 Artist10 Foreword Introduction Translator Photographer Digital Media Format1 Digital Media Format2 Digital Media Format3 Digital Media Format4 Digital Media Format5 Digital Media Format6 Digital Media Format7 Digital Media Format8 Digital Media Format9 Digital Media Format10
item_sku external_product_id external_product_id_type item_name manufacturer product_description update_delete author binding publication_date edition standard_price quantity condition_type condition_note product_tax_code expedited_shipping will_ship_internationally standard_plus delivery_schedule_group_id generic_keywords1 generic_keywords2 generic_keywords3 generic_keywords4 generic_keywords5 main_image_url main_offer_image offer_image1 offer_image2 offer_image3 offer_image4 fulfillment_center_id package_height package_width package_length package_dimensions_unit_of_measure package_weight package_weight_unit_of_measure unknown_subject language_value illustrator signed_by dust_jacket_description pages series_number collection_name editor preface colorist compiler composer1 composer2 composer3 composer4 composer5 composer6 composer7 composer8 composer9 composer10 creator drawings painter reader series_editor technical_editor adapter afterword artist1 artist2 artist3 artist4 artist5 artist6 artist7 artist8 artist9 artist10 foreword introduction translator photographer format1 format2 format3 format4 format5 format6 format7 format8 format9 format10
10162513 0452011876 UPC Olympus Camedia C-50 Digital Camera Sony J.K.Rowling paperback 1994 http://www.companyname.com/images/1250.main.jpg