@Switch BlaydeOn SOL, it's always been 14 to 18, quite literally 'teens'. For most coming of age stories, this allows the story to cover the typical range of ages of siblings, unrelated to any adults they may interact with. Thus it's essentially a cover-all description, meant to cover any relationships involving teens, either serious intimate relationships or one-night stands. But it's non-exclusive, so you'd also list whatever other particular tags happen to apply. Though of course, if there's no actual sex described (i.e. no subtle 'behind closed door' episodes). Thus for slowly developing romantic involvements, you could either include them or not just to highlight the relationships covered.
Which is precisely what confuses most new SOL authors, the fact the tags are alternately specific and non-specific.
Which gets tricky during Coming-of-Age stories in the late 70s (1970s), where for many of us, we could legally drink for slightly less than a year, then couldn't since we were no longer 'old-enough to drink'. It never stopped us, as in my case, it was easy enough to drive across the border to Wisconsin and order anything we wanted to take home anyway.
Strange times. In the U.S., the 'national' laws didn't always cover those states which didn't elect to adopt them, while others followed them religiously. So mostly, for those COA stories which did cover that period, they'd simply adjust the specific ages or resident stages so it wouldn't screw up the stories.