A bit list in wxCLIPS is a way of specifying several window styles. It derives from C and C++ syntax, where by defining identifiers with carefully chosen binary numbers, it is possible to combine several values in one integer. In wxCLIPS, you use similar syntax to C, but enclose the list in quotes:
"wxCAPTION | wxMINIMIZE_BOX | wxMINIMIZE_BOX | wxTHICK_FRAME"