Colons and semi-colons-is this correct!?

[Manana]

Can I just clarify that what I'm teaching about punctuation is correct!

Semi colons
I think you should use a semi colon when linking two sentences together which are closely connected but could be replaced by a full stop. The second sentence must be a stand-alone sentence in its own right.

Semi colons can also be used in lists where part of the list may have more than one word, eg I have been to New York, America; Paris, France; Madrid, Spain and Edinburgh, Scotland.

Colons
These can be used after names in playscripts (Macbeth: I have a feeling it's all going to go horribly wrong for me), or a list (I have packed the following: sleeping bag, torch, wellies and mug.)

They are also used to explain the first part of the sentence and often the two parts of the sentence are equally weighted, eg The battle was over at last: everyone was dead.

Or could you say... The battle was over at last; everyone was dead.

Hmmmm

Do you all agree with these and are there any other uses?

[aargh]

Lynne Truss is very good on this sort of thing, try her book Eats shoots and leaves.

"The main place for putting a semicolon is between two related sentences where there is no conjunction such as "and" or "but", and where a comma would be ungrammatical." The semicolon tells you there is a close relationship, as in this example:
Tom locked himself in the shed. England lost to Argentina.
Tom locked himself in the shed; England lost to Argentina.

She also refers to your second usage of a semicolon, in list of items with extra defining words, as:
"It performs the role of a special policeman in the event of comma fights."

There are "annunciatory" colons: which proclaim the aproach of something.

There are "Yes!" colons which connect a qualifying phrase to the first part of the sentence.
"This much is clear, Watson: it was the baying of an enormous hound."

There are "Ah!" colons where the colon reminds us there is probably more to the initial statement than has met the eye:
"You can do it: and you will do it."

In your battle example I would tend to go for "the battle was over at last: everyone was dead." because the colon is classically used as a fulcrum. the twist in the tale makes the colon better because a semicolon likes the 2 halves to be thematically similar.

Anyway, read the book, she has a whole chapter on this plus plenty more on all other aspects of punctuation.

[aargh]

H'm just got a PM that refers to the New Yorker shedding serious doubt on the accuracy of Lynne Truss.
I'm off to check it

[faitaccompli]

Sir Ernest Gowers "Complete Plain Words" is bound to have the answer!