Acadiasoft’s Initial Margin Exposure Manager. See the AcadiaSoft website for more information (https://www.acadiasoft.com/solutions/) or this PDF: https://www.acadiasoft.com/wp-content/uploads/2018/08/AcadiaFSIMExposure.pdf
In some margin agreements this is called an independent amount. The concept comes from the futures market where you must make a deposit into your margin account at the beginning of trading. For OTC products it means an amount of margin representing risk in an entire portfolio. This can be recalculated any time, but mostly at the end of each business day.
The International Swaps and Derivatives Association is a club for firms who trade OTC derivatives. ISDA provide the global framework for trading these products along with an active role in developing technology to improve the working of the OTC market.