I'm taking notes in a largish org-mode file that has the following structure: * Toto, A Notes about Toto. * Titi, C Notes about Titi. * Tutu, A Notes about Tutu. I'd like to sort the file so that all the headings with A precede the headings with B, which in turn precede the headings with C, and so on. Is there an automated way to do that with org-mode?