This blog a gives clear picture about the functionality of the feature Attachments > Add a Link in the app Manage Purchase Orders.
In the app Manage Purchase Orders:
Attachments and URLs can be added by clicking on “Add a Link”.
Name of the attachment will be same as the name of file attached.
While adding a link ensure you add a valid URL. An error message will be displayed if the URL is not valid. Description can also be added and is optional. If not specified, the description will be saved same as the URL.
In the app “My Inbox” for Approvers
Each file attached comes as an individual attachment and the attachment name will be a file prefixed with ‘H_’.
All the URLs added are consolidated in a single attachment (text file). In this text file all the URLs are separated by line breaks. The attachment name of this text file will be ‘H_URL_Attachments.txt’.
When the URL attachment ‘H_URL_Attachments.txt’ is clicked from the approver’s My Inbox, a file with name PO_XXXXXXXXXX_URL.txt where XXXXXXXXXX refers to purchase order number is downloaded. You can see all the links in this text file.