How to interpret TSkinWeightInfo

I’m trying to get all vertices attached to a bone. From what I can tell it’s stored as a flattened array with a (typical) stride of 8, the first 4 uint8’s being the influence bones and the latter being the weights. My best guess for getting the bone number attached to the weight is

UKismetMathLibrary::Round((NumBones - 1) * (TSkinWeightInfo->InfluenceBones[j] / 255.0f))

with the weights being in the range of 0-255.

Should the weights be averaged across all 4 weights (totaling 1), or does a weight of 255 supersede all other weights (rigid Bone)