@@ and @atchar{} ¶@@ produces a single ‘@’ character in the output. Do
not put braces after an @@ command.
@atchar{} also produces a single ‘@’ character in the
output. It does need following braces, as usual for alphabetic
commands. In inline conditionals (see Inline Conditionals: @inline, @inlineifelse, @inlineraw), it
can be necessary to avoid using the literal ‘@’ character in the
source (and may be clearer in other contexts).