Open Enterprise Portal PO Screen

Hello,

I am using AX 2012 R3 with Enterprise Portal.

I am using AIF web services to get a list of Purchase Orders for a user. I would like the user to be able to click the PO number and open the same PO on Enterprise Portal. 

I looked at the query string of the PO and am able to figure out the different values in the query string such as WMI, WCMP, WTID, WKEY, etc. This data is either static or available in the data returned by web services. However, I am not able to figure out the value for WHPV. This is a long, 64 character, string that is different for each PO. If this is not passed in the URL you get a "invalid URL or URL has expired message".

What is WHPV parameter?

Thanks