Attachments: Up to 2 attachments (including images) can be used with a maximum of 512.0 KiB each and 1.0 MiB total.
It's the same as you can use in Eikon Excel. You can view the explanation in Eikon Excel Formula Builder or in Data Item Browser app in Eikon by clicking on the question mark icon next to a date field in the Parameters tab. Here's the screenshot.
Trying to fetch Close Bid Price for CMO tranche from Python
How to get all investors for a list of stocks, historically with the python API
Company trees don't match in Eikon online tool and the Eikon Proxy API
Retrieve Commodity Flows data using Python API
Download API Proxy Python for Windows.