Currently we are integrating with a 3rd party system. This includes data sent to this 3rd party where the customer is able to see it. My current task is to provide visual documentation (PDF) about which values from our tool land where in the target system. What I am struggling with is the fact that screenshots of both systems require the full screensize, otherwise it is hard to read the field names.
If there are many fields, just use a mapping table with source an destination, and provide the two separate screenshots in reasonnable size, in case someone wants to see where a field mentionned on the table is on the screen.
If there are no labels on all the fields, number the missing ones in the separate screenshots and also provide these numbers in the mapping table.
The solution of showing the screenshots side by side with arrows from the one to the other is only an option if there are a few fields, and no full screen (or if groups of fields can be illustrated in this manner).