Problem understanding dates in English

[Patricia]

For quite some time I've had this little problem while proofreading translations. I don't know if I'm getting it wrong or the translators who I'm proofreading are getting it wrong:

If I have a date, let's say 1870s, ¿Does this mean the decade of the '70s or the year 1870 alone?

Same goes for, let's say the 1900s: ¿Does this mean the decade of the 1900s or the 20th century?

[skye]

As far as I know 1870s means the decade of the 70s (1870 - 1879)

And 1900s means the first decade of the 20th century (1900 - 1909).

[JackFrost]

The "contraction" of decades always involves with the 20th century.

1870s stay 1870s (1870-1879), but never 70s.

But...

1970s can be 1970s or 70s (1970-1979).

When you see an "s" after the year numbers, it means the decade, not just one certain year.

[skye]

It would be difficult to understand which decade you mean if it wasn't so.

[Patricia]

Thanks guys. So it seems my understanding of it is correct, and that I have to teach those translators to avoid those mistakes.

[skye]

Hehe, I know that dilemma. When everyone else around you starts using the wrong form you start wondering if you're the one who's been wrong all these years and not them.