A number of subtleties in the handling of backslashes (which the reader will no doubt have encountered in his practical use of UNIX) are still not immediately apparent. Since “maptab[c]” is zero for “c == ‘\’ ” (octal value of 134), all backslashes get copied into “canonb”. A single backslash will be subsequently overwritten if the following character is to be asserted (as in the case of ‘#’ or ‘@’ or eot (004), or if the case of an alphabetic character is to be changed for an upper case only terminal.
