What is the syntax to access sub fields?

What is the syntax to access sub fields?

Hello community.

I need to use the field [salesorders.salesorder_id] returned when I Fetch Purchase Orders (from inventory).  As an example, I can see that this value is returned

salesorders : [
   {
   date      : "2024-10-22",
   salesorder_order_status      : "onhold",
   salesorder_number      : "P.SO-10299",
   salesorder_id      : "99999000002258119",
   order_sub_status      : "",
   shipment_date      : "",
   salesorder_status      : "onhold", 
      }
 
How do I use the value in sale orders.salesorder_id as the search value for the next flow step?  the only option to select is ${fetchPurchaseOrder_1.salesorders}.  I attempted to use ${fetchPurchaseOrder_1.salesorders.salesorder_id} but that didn't return a value.  

If someone could help me out with the correct syntax or method, that would really be appreciated.
Thanks
Chris.