Final answer:
The primary purpose of DA Form 581 TAR is to document and report training activities conducted by military units.
Step-by-step explanation:
The primary purpose of DA Form 581 TAR, which stands for Training Activities Report, is to document and report the training activities conducted by military units. It is used to track and record important details such as the type of training, the number of soldiers involved, the location, and the duration. This form helps ensure that training activities are properly documented and that the necessary data is collected for analysis and future planning.