I don't usually use printf and friends, but it appears the directives are case-insensitive:
#;1> (sprintf "~a~%" "asdf") "asdf\n" #;2> (sprintf "~A~%" "asdf") "asdf\n" #;3> (sprintf "~S~%" "asdf") "\"asdf\"\n" #;4> (sprintf "~s~%" "asdf") "\"asdf\"\n" #;5> (sprintf "~b~%" 42) "101010\n" #;6> (sprintf "~B~%" 42) "101010\n" The code appears to suggest it too: https://code.call-cc.org/cgi-bin/gitweb.cgi?p=chicken-core.git;a=blob;f=extras.scm;h=921706b477d63a53c1e0807da43c905e0114669b;hb=HEAD#l383
