A new acquaintance of ours arrived in Abu Dhabi just ahead of her 30th birthday, tomorrow. She didn’t seem to mind the idea of turning 30. In fact, she said she was tired of being in her 20s.

Which set me off on reverie about how “30” was once a far more significant number, especially in the lives of print journalists.

First, the age thing. Americans on the high side of age 55 probably have clear memories of a time when turning 30 was considered a major life event. And not for the good.

I was perhaps 27 when a colleague turned 30, and friends of his put on an extravagant party — a wake, really — for him. A practice not at all uncommon at the time.

The idea being that 30 was when you said goodbye to youth, got busy with the responsibilities of life (whether or not you wanted to, as depicted in the whiny and self-absorbed TV series “thirtysomething”) and, yes, had to confront the reality of your own mortality.

The gifts one brought to a 30th birthday party had everything to do with advanced age. Denture cream. Laxatives. Hair dye. A magnifying glass. (For reading tiny print, of course.) Adult diapers. Because 30 was such a major turning point.

Thinking back, even in the 1970s the Big Three-Oh was no longer the threshold it had been, and perhaps society was acting on the assumptions — and maybe the realities –  of a previous time. Maybe from early in the century, before antibiotics were common, and people actually did die young.

Now? No point in arguing against the notion that, in the First World, anyway, 30 is the new whatever people say it is. Maybe 20. No more than 25.

Life decisions are being put off. Those new thirtysomethings probably have not married and probably do not have children. Because the press of time seems less intense, they may not have settled on a career, and are pursuing yet another degree or plan to take a leisurely trip around the world. (Some of that is a function of weak economies, as much as the belief among younger people that they all will live to 80, at the least.)

And a corollary to that notion is that 40 is the new 30 and 50 the new 40, etc., notions which aren’t always quite true, but for people who do the basics of taking care of themselves, it often works out that way.

The other meaning of “30” comes from print journalism. To write “30” or “-30-” in text meant “the story is over.”

Wikipedia even has an entry on this, which advances a couple of different stories on where -30- originated.

The one that sounds most logical suggests that when stories were written by hand, “X” indicated the end of a sentence, “XX” the end of a paragraph and “XXX” the end of the story.

In Roman numerals (more about them later), XXX means 30. So -30- at the end of the story was the same as writing XXX, and generations of print journalists passed down the tradition.

(Though “ends” or “endit” are among other methods still used by newspaper reporters to indicate the finish of a story.)

And why do we need to indicate the end of a story? From semi-ancient times, when the transmission of a story via telegraph or cable or some other system was not always reliable, and not until you reached a signal from the author could a publication be sure it had gotten the whole of the transmission.

So, “30” has a couple of meanings for ink-stained hacks of a certain age. It was a turning point in life, as well as the end of a day’s work.