apostrophe misuse

In France, in order to make words look more anglo-saxon, there is the habit of sticking an apostrophe and an 's' at the end of words. A shop selling English furniture is thus called 'Interior's'.

I would like to inform my French readers, however, that the situation is not better, perhaps even worse, back home in England. Which is even more pathetic, given that in a country where English is the native language, a large proportion of the population has absolutely no idea when and how to use the apostrophe.

's is known as the anglo-saxon genitive and is used to denote possession - the 's goes at the end of the possessor, not the possessed:

The manager's car = the car that belongs to the manager

When a word is already a plural, you put just an apostrophe after the final s, without adding a second s:

the managers' cars = the cars that belong to the managers

There are even websites that try to combat the misuse of the apostrophe. Take a look at the following for example:

www.apostrophe.fsnet.co.uk

There are some exceptions to the apostrophe rule, however. These would be in situations where adding an 's' to make a plural would be confusing. For example, we often talk about a list of do's and don'ts(a list of things to do and not to do).
If we simply added an 's' to 'do' to make it a plural you would get 'dos' which looks like an incorrect spelling of the third person, 'does' or the abbreviation of 'disk operating system'.
Also, initials can take an apostrophe in order to avoid making the plural 's' look like one of the intials. For example, it would be OK to write the plural of CD, CD's. If there were no apostrophe, it would look like three initials, CDS.

I don't know if my exceptions here are officially recognised, so if you strongly disagree, let me know!