C_IFS
if (ctype(c, C_IFS)) {
while (Xlength(cs, cp) && ctype(cp[-1], C_IFS)
&& ctype(c, C_IFS)))
while (*p && ctype(*p, C_IFS) && ctype(*p, C_IFSWS))
if (t & C_IFS) {
ctypes[i] &= ~C_IFS;
ctypes[0] |= C_IFS; /* include \0 in C_IFS */
setctypes(s = str_val(vp), C_IFS);
setctypes(" \t\n", C_IFS);