The Payment Attachment feature allow customers to upload files as part of the checkout process. This may be vital for stores selling products or services that need verification or more information before completing the order.

Features of the Payment Attachment during Checkout Module:

1. File Upload Fields:
   • Enables customers to upload files at specific stages in the checkout process, for instance, after shipping details have been entered but before the final payment.
   • Supports multiple file types of images, PDFs, Word documents, and more. 
2. Configurable for Specific Products:
   • Admins can customise which products need attachments for checkout, making it unique to the product category or individual items. 
3. Customisation:
   • Store owners can customise their instructions or labels for attachments (e.g., "Please upload your business license to verify"). 
   • Customised maximum allowed file size and approved file types. 
4. Validation Rules:
   • Ensures that files are in the right format (e.g., only PDFs, images, etc.) and within size requirements before it accepts the submission.
   • May also include constraints such as a minimum number of pages for a PDF or a specified resolution for an image.
5. Admin Management:
   • Attachments by customers can be viewed easily through the order management interface.
   • Documents uploaded are associated with specific orders and can be accessed through the order details page.
6. Secure File Handling:
   • The module makes sure that files uploaded by the customers are stored securely to maintain privacy and adhere to data protection regulations. 
   • Files are generally found in a dedicated folder, along with access controls appropriately implemented. 
7. Support for Conditional Logic:
   • Conditional logic would be helpful to trigger the upload option considering the type of payment being selected or any other kind of action being taken at checkout by the customer. 
8. Customer Notifications:
   • Automatically, customers get notifications that they have submitted attachments successfully.
   • Even admins will receive notifications based on the document being subject to review or approval or both.

Benefits of Payment Attachment during Checkout Addon:

1. Streamlined Document Collection:
   • It simplifies the collection of essential documents directly through the checkout process and avoids manual follow-ups.
2. Improved Customer Experience:
   • With this kind of document upload interface that is easy to read and understand, there's a better customer experience by eliminating confusion and also helping them trust the whole process. 
3. Increased Accuracy:
   • File collection in real time as the customer goes through checkout will minimise chances of either missed or wrong documents submitted due to the prompt presented during checkout to fill all fields and then complete the order. 
4. Enhanced Security and Compliance:
   • Sensitive documents can be uploaded and stored securely so that businesses can stay compliant with industry regulations, such as GDPR for European customers or PCI DSS for payment data. 
5. Customisable Workflow:
   • The file upload process can be customised to fit the business needs, such as identity verification, customised product designs, or customer support tickets, thus increasing operational flexibility. 
6. Efficient Order Processing:
   • Admins can view the files uploaded by customers right from the order management interface, hence easy to check attachments and no delay in fulfilling the orders. 
7. Cost Savings:
   • The automation of the document collection process will save the administrative time and cost of collecting, verifying, and following up on each document manually. 
8. Reduced Errors and Fraud:
   • With added document validation features, businesses can avoid the possibility of accepting fraudulent orders as all the required verification documentation is submitted in advance. 
9. Professionalism:
   • Offering this functionality to customers adds a layer of professionalism to the store, demonstrating that the business takes customer interactions seriously, especially in sectors that require documentation (e.g., wholesale, personalised products, high-value items).

The Payment Attachment during Checkout addon for CS-Cart is a useful tool for stores, allowing them to collect extra information or documents from clients right at the checkout point, doing this more efficiently, securely, and professionally during order fulfillment. The module's benefit comes not only for the store owner but for customers too.