The definition and abbreviation for Potentially Hazardous Food (Time/Temperature Control for Safety Food) or PHF/TCS should be modified to drop the reference to potentially hazardous food and PHF.
Yes, as a treat apples are fine for chickens. Some will say it is best not to feed them too many apples as the seed of an apple has a small amount of arsenic in it.
Apple has a light, fruity, slightly sweet aroma and is commonly used with pork and poultry. I especially like to use it with pork ribs. It can be mixed with other smoke woods like oak and cherry with good results. Cherry is one of my favorite woods to use with chicken. It has a slight red color and a subtle, sweet, fruity flavor. It goes well with beef, pork, and poultry and can be mixed with oak and apple. Guava, a member of the Myrtle family, is a fruit wood from Hawaii and other tropical regions.