What does MFP use as guide for Vit C allowance?

BlueBaron37

I have two different brands of fresh orange, both have different scales of vitamin C percentage, both are not using the same scale, the suermarket brand, is closest to what I saw on a site on the net with 94% 75mg.

But I wouldn't know where the 75mg came from as a 100%, I'd like to know what guild MFP uses.