High school records and graduation. Schools can't deny admittance to illegals, so they built a school academic record like anyone else.
It is easier then you might think.
Since they are not checking citizenship in schools, all they have to show is their transcripts from a in state school.
I think this law is an end run around the requirement to show citizenship. If they did not allow illegals the same rights as legal in state students they would then have to have a way to check citizenship. They do not want to do this so the easy way out is ignore citizenship and base it on residency (which is where the school transcripts come into play). For liberals it is a win win solution. For the California taxpayers it is a lose lose, but liberals never care about other people's money
They aren't totally undocumented. Only their citizenship is undocumented.
They can show that they've been in the public school system for 5 years. They can show that they've been committing identity theft and using someone elses social security number to work at a local job for 5 years. They can show they got a mortgage from bank of America and own a home and have four other families renting from them in that home. lol