Thanks for clarifying your concern ... HT and KD do not indicate pressure treated, although the heat treating does kill critters. The pressure treating process requires infusing the wood with chemicals. Your stamp does NOT indicate pressure treating.
The stamp you want is a "UC" stamp. UC2 will be the lowest grade of pressure treated lumber, and this means it's protected from weather but still subject to moisture damage. It's best used in interior construction. UC3B is best for decking, railing, and fences as it's treated to withstand prolonged moisture. UC4A is similar, but can be used in applications where the wood will be underground as well, such as privacy fence posts. UC4B is best for permanent foundations and utility poles as it will resist moisture and decay if placed underground.
This might also be helpful: http://www.cpsc.gov/PageFiles/122137/270.pdf