Peter T. Daniels wrote:

>
> > Is there a reference for the "newfangled" usage? I rarely see it and
> > always consider it incorrect, but I am willing to stand corrected....
>
> Chicago Manual of Style, at least since the 13th ed. Always use 's
> except on names that end with the "eez" sound (Aristophanes') and a few
> stereotyped cases -- in Jesus' name, for conscience' sake (I think there
> are half a dozen exceptions).

I don't have that book handy (but will take a look next time I am
someplace that does). But you inspired me to search online and I found
this at www.chicagomanualofstyle.org:

http://www.chicagomanualofstyle.org/cmosfaq.html (site has frames -
search on apostrophe and then scroll to the following passage)
-------------------
Q. When indicating possession of a word that ends in s, is it correct to
repeat the s after using an apostrophe? For example, which is correct:
“Dickens’ novel” or “Dickens’s novel”?

A. Either is correct, though CMS 15 recommends the latter. Please
consult 7.18–22 for a full discussion of the rules for forming the
possessive of proper nouns, including exceptions and examples. For a
simpler statement of the rule, see paragraph 5.26. For a discussion of
the alternative practice of simply adding an apostrophe to form the
possessive of proper nouns ending in s, see paragraph 7.23.
-------------------

So your explanation and summary about is incomplete for someone looking
to it for practical usage info although it does serve as an answer to my
original question seeking a citation.

I wonder if other Style Guides have adapted similarly as this usage does
not seem very widespread in my readings ....

>
> > > But I don't see how it can be other than kids' activities.
> >
> > I think "kids activities" is kind of colloquial to begin with... stuff
> > that lids do on a playground could be "kids activities" or "kid
> > activities" without loss of meaning or nuance I think. The latter would
> > be the plural of the noun phrase "kid activity" I think.
>
> Sounds Brit.

Maybe - it is idiomatic to my ears at least.

How about "adult activities" such as "when you are 18, you will be able
to participate in adult activities such as voting"?

Best,

Barry