_____________can be used as templates for future mail merge needs

The answer is: mail merge documents.

Mail merge documents can be used as templates for future mail merge needs. These documents are pre-designed templates that contain placeholders for dynamic data, such as names, addresses, and other information. By using a mail merge document as a template, you can quickly and easily create new documents with the same layout and design, but with different data inserted into the placeholders.

For example, if you have a mail merge document for a company's annual report, you can use it as a template for future reports by simply updating the data and re-running the mail merge process. This saves time and effort, and ensures that your documents always have a consistent look and feel.