Some labels are marked as N/A why?

[jiashenC]

As an initial step for cost-based optimizer, I want to add SSD model along with FasterRCNN.

I wonder why some labels are marked as N/A for FasterRCNN like here?

[xzdandy]

@jiashenC https://pytorch.org/docs/stable/torchvision/models.html#object-detection-instance-segmentation-and-person-keypoint-detection

[jiashenC]

Interesting. So COCO has 81 classes including background. What is 91 classes? And the model is defined to be 91 classes, 10 of those are actually not used (return N/A).