It did exist, you got 90 days within a year each time you entered Thailand, -now you only get 90 days one time.
Non O-A is basically the same as the previous Non O. You get one year upon each entry within one year, -two years in total.
The main requirements are the same, -minimum 50 years of age and income/funds 65K/800K baht, but the Non O-A requires a mandatory health insurance/certificate and a police check up as well.
Both visas are based on retirement/50 years of age and passive income/funds and you’re not allowed to work or do any business on this basis for your stay.
Previously you could get a regular one year 90 days Non O visa with multiple entries which gave you up to 15 months in Thailand. As Graham states this is phased out in the new e-visa system and you only get a 90 days Non O visa with single entry and one year Non O-A visa with multiple entries.