Buy-at-Close

Please download and overwrite the updated QuickRef for v6.9 which now contains all V7 equivalents. I'm 100% sure you'll find your question answered there:

https://wl6.wealth-lab.com/Forum/Posts/Download-Version-6-9-QuickRef-with-Version-7-Equivalents-40609

For your reference:

CODE:
PlaceTrade(bars, TransactionType.Buy, OrderType.MarketClose);