CTAN Markdown: Quotations
Qutotations are familiar to you from emails. In good old days qutations in emails have been started with a greater sign and a space at the beginning of the line. This kind of markup is supported by markdown as well.
> abc > def
Quotation can be cascaded. The next level is just marked in the same way inside a quotation line.
> abc > > ghi > > xyz > def