Use a colon to indicate that material is to follow. The material that follows may be a summary, a list, a complete sentence, a question, or a quotation.
If the items in the material that follows the colon consist of only one or two words, they may be separated simply with commas:
If each of the items in the following material consists of several words, you will probably be wise to separate them with semi-colons:
Theoretically, all the material that follows the colon is ‘suspended’ from it as the completion of the introductory words. When there is only a small amount of material, it can be presented conveniently within your normal paragraph layout:
But often you will want to help your reader see the elements in your list, and you will use ‘display’ tactics to do so – you will inset the list vertically. Again theoretically, you should retain the same pattern of punctuation, with intermediate semi-colons, and a ﬁnal full stop:
However, punctuating displayed text is not as straightforward as I have suggested. There are two complicating factors:
• when we use display technique to help with the completion of a statement, we are tempted to ‘hang’ overwhelming amounts of information after the colon;
• in technical writing, we use an invoicing colon not only to indicate continuation/completion/extension of a statement but also simply to signal that a special display of information is about to appear.