I have downloaded the OpenImages version 6 image sets (train, validation, test) from CVD Foundation as per instructions from the OpenImages homepage. The OpenImages homepage states that there are 600 boxable object classes in the dataset.
When I sift through the entire list of training set bounding box annotations from https://storage.googleapis.com/openimages/v6/oidv6-train-annotations-bbox.csv, it turns out 599 unique label names. So, that is one short of the supposed 600 classes.
If I download the boxable class names from https://storage.googleapis.com/openimages/v5/class-descriptions-boxable.csv (this is linked from the OpenImages version 6 page despite its apparent version 5 origin), this list contains 601 classes.
It seems neither of the above approaches identify the correct 600 classes, so how do I correctly identify the "official" 600 classes?