> Playing around a little with changing the escape character, > I'm confused...
It seems the situation is not entirely symmetrical between "\" and "x" as escape characters. With "\", "\\" is a backslash and "\x" is the extra-line-space function. With "x", "x\" is also a backslash (though groff warns that it is ignoring the escape character), and "xx" is still the extra-line-space function (and needs an argument, hence the error you got). In *copy mode*, however, "xx" appears to be copied as "x", so when defining macros you use, for example, "xx$1" instead of "\\$1"; an "x" at the end of the line means an escaped newline; etc. I found that to get the extra-line-space function, you must use "xxxx", which gets copied as "xx" and is interpreted as function "x" when the macro is reread. Most functions are *not* interpreted in copy mode, and need not be extra-escaped. E.g., for the overstrike function you can simply use "xo'abc'" instead of "xxo'abc'", although the latter does not seem to hurt. So with the backslash as escape, you can simply say "\x'10p'". The exception seems to be when the function letter is the same as the escape character, which kind of makes sense.
