This may be common knowledge but I haven't seen it written anywhere. While combing through the code (textual.cc instance_t::read_next_directive() to be specific) I found that ledger will allow a few different kinds of comment characters. You can use # | * AT THE BEGINNING OF A LINE and that line will be ignored (print will also ignore it as usual). I have added it to the docs.
-- Craig, Corona De Tucson, AZ enderw88.wordpress.com
