A block quote marker consists of 0-3 spaces of initial indent, plus (a) the
character >
together with a following space, or (b) a single character >
not followed by a space.
The following rules define block quotes:
Basic case. If a string of lines Ls constitute a sequence of blocks
Bs, then the result of prepending a block quote marker to the beginning of
each line in Ls is a block quote containing Bs.
Laziness. If a string of lines Ls constitute a block quote with
contents Bs, then the result of deleting the initial block quote marker
from one or more lines in which the next non-whitespace character after the
block quote marker is paragraph continuation text is a block quote with Bs
as its content. Paragraph continuation text is text that will be parsed as
part of the content of a paragraph, but does not occur at the beginning of
the paragraph.
Consecutiveness. A document cannot contain two block quotes in a row
unless there is a blank line between them.
Nothing else counts as a block quote.