Vintage Sasson Modern Basics Acid Jeans, Size 12

Not sure how the size works for Sasson Jeans. The Tag reads Size 12, I would assume it would be a Junior size 12 ... that is not a women's 12 as I am a 29 or 30 or size 6 and these are too small for me. Also note, there is not stretch factor for these jeans. As I researched these jeans, Sasson left the company in 1976 so perhaps sizing back then was way different?? Vintage Sasson Acids Size 12 100% Cotton