Hi niloofarsabouri
I think the voc is used here for ease of use. since the dataset is pre-made. Also it helps show how to convert between formats since many datasets exist in VOC. According to yolov6 training notebook:
If you are using a custom dataset, you will have to prepare your dataset for training YOLOv6 Wiki. Once you have set up YAML and sorted labels and images into the right directories, you can continue with the next step.
Luckily, we are using VOC, for which YAML already exists. If you inspect the YAML. We'll be the following tutorial on how to train YOLOV6 on the VOC data set.
Thanks,
Jaka