(BLOCK (PARA (TEXT "A citation key references some external material that is part of a bibliographical collection.")) (PARA (TEXT "Currently, Zettelstore implements this only partially, it is ") (FORMAT-QUOTE () (TEXT "work in progress")) (TEXT ".")) (PARA (TEXT "However, the syntax is: beginning with a left square bracket and followed by an at sign character (") (FORMAT-QUOTE () (LITERAL-INPUT () "@")) (TEXT ", U+0040), the citation key is given.") (SOFT) (TEXT "The key is typically a sequence of letters and digits.") (SOFT) (TEXT "If a comma character (") (FORMAT-QUOTE () (LITERAL-INPUT () ",")) (TEXT ", U+002C) or a vertical bar character is given, the following is interpreted as ") (LINK () (ZETTEL "00001007040000") (TEXT "inline elements")) (TEXT ".") (SOFT) (TEXT "A right square bracket ends the text and the citation key element.")))