The question to adherents of semantic HTML markup.
How to typeset a multiline quotation? It is clear that the blockquote tag, but then I see the difficulty in a very common case, when in the last paragraph, after the quotation is some text: this is usually an indication of source in the brackets, the sign of a footnote or even a trivial point outside the quotes. What to do with this text?
On the one hand, it is not part of quotes, so inside the blockquote tag, it is nothing to do. On the other hand, it is part of the last paragraph of the grouped in the same tag.
Very bad becomes, if put quotation marks using CSS; then they seize and this text that is absolutely wrong. You can, of course, to thread the needle by wrapping the tag in a span, which is set to absolute positioning and a small indent on the left; then it falls out of context and go after the final quotation marks. But it has all sorts of undesirable side effect: the emergence, in certain situations, the scroll bar does not seem the appropriate order of text copying...
In General, you want solutions and semantically correct, to make it look right — or at least reasons why it is impossible.