Code

var vintRecordNumber as Int
var vintCurrentPosition as Int
var vintResultSetTotal as Int
var vmnyBalance As Money
var vintCurrentPosition = @FormResultSetCurrentPosition( "LineItems" )
var vintResultSetTotal = @FormResultSetTotal( "LineItems" )

//Verify that we're not currently adding a record to the subset
If vintCurrentPosition <= vintResultSetTotal Then
{
	//Set an initial balance.  This value should likely be obtained from a field in the parent form.
	vmnyBalance = 300

	//Anal variable initialization.
	vintRecordNumber = 0

	//Loop through all of the records in the subform.
	While vintRecordNumber < vintResultSetTotal
	{
		vintRecordNumber = vintRecordNumber + 1
		vmnyBalance = vmnyBalance - @TOMONEY(@FormFieldValue("LineItems", "Price", vintRecordNumber ))
		FormFieldValue("LineItems", "Balance", vintRecordNumber, vmnyBalance )
	}
}