To meet blood requirements for enrollment one must be first descended from an enrolled member. And here is a chart that I found that explains the blood quantum as provided by the BIA. I didn't find this at their site. Keep in mind this only goes to the xx/64. I know some people whose quantum reads xx/128. Enrollment requirements are determined by the tribe. This chart is for their use. And for the mathematically inclined, check the rounding of the fractions.
I'm on the rolls as 1/2, I should be 15/16. My father is non Indian according to the enrollment requirements of my tribe, even though he is 7/8 Anishinabe. He is from another band, not considered part of our band. Culturally, he is Anishinabe, he speaks Anishinabe, though not quite as fluently as some would like. My mom is full blood according to the requirements of my tribe, Band I should say. I and my siblings can't be enrolled in his Band/tribe as my mom is considered non-Indian in that band, we don't have enough blood to meet the 1/2 requirement. My sons would still be enrolled in their father's Band if I hadn't been enrolled: I'd be considered non-Indian, even though I am 15/16. Their children would be eligible to be enrolled, even if the mother was non-Indian as half my son's blood clears the 1/4 requirement. Make any sense to you yet?
Well, join the club. It gets mind-boggling at times. And the issue get clouded further because the enrollment, as least in my tribe/band, requires a birth certificate and a notarized statement and/or marriage certificate and a direct link to an enrolled member on one of those lists. And that's another can of worms. You may have read one or two rants on the subject.
I've had a talk with my nieces, nephews and sons. Reminded them when they chose a "non-Indian" as partner/spouse that their child may or may not be eligible for enrollment. They knew the kids would still be considered Indian, at least in my eyes, though they wouldn't have any claims as an enrolled Band member, unless blood quantum for my Band/Tribe was changed. And therein lies the issue behind enrollment and Federal recognition. Another can of worms; or would that be rant?
I prefer "non-Indian" when speaking in certain contexts and now you know the reason why. And you also know why it is difficult to use the term Indian, Native American, Indigenous. Most tribes are referring to themselves by their own names. Time for it, I say. And some think we are a simple people. teehee.