The append geoprocessing tool used to put input features as the first parameter and target features as the second. In a recent update, they switched. I'm not certain, though it may have to do with batch inputs and reserving space for the target feature slot to always remain accessable without scrolling? Conjecture.
This is opposite of intuitive, especially since so many other gp tools standardly put the input features as the first ordered item in the tool interface. Please switch these back (unless there's a super duper good reason they switched in the first place)
