Ohio has very clear criteria for gifted identification:
Chart of Approved Gifted Identification/Screening Instruments
Identification of Students Who Are Gifted in Superior Cognitive Ability
Identification of Gifted Students Using Above-Grade Level Testing
Identification of Students Who Are Gifted in Creative Thinking Ability
Identifying Students Who Are Gifted in the Visual and Performing Arts

Districts choose which tests from these approved lists they will use for screening and identification, and they choose which students to screen. Parents can have their children participate in talent searches or have outside testing done for identification if the school didn't select their child for testing.

This doesn't mean that the district will offer any kind of services or programming for gifted students. It also doesn't tell districts how to determine which gifted students receive services if gifted services are provided and there are more students identified than there are spots in the program.

Having these criteria are helpful for parents to advocate for gifted identification and acceleration. I used my DD's EXPLORE results to begin the process that resulted in her subject-acceleration in math this year.