UPDATED on February 23, 2016
If you have a CSV file with contact information you would like to add into attachedContacts, you can use the File Import feature to easily add them.
For example, you may have a long list of potential customers from a trade show or advertisement that you want to start tracking. While you could add each of them in manually, you can save significant time by doing a File Import instead.
From the Contacts grid simply click on File Import and follow the step-by-step instructions on your screen.