> Why is pdfcsplain calling luatex for you? csplain has five commands: (1) csplain (2) pdfcsplain (3) luacsplain (4) luatex -fmt=pdfcsplain (5) xetex -fmt=pdfcsplain (1) and (2) are probably equivalent and use pdftex. (3) and (4) are probably equivalent and use luatex. (5) use xetex. Best, Akira