* We reject leading underscores in bareword.  No sensible reason why.
     * Might be inspired by reserved identifier rules in C, which of course
     * have no direct relevance here.
     */

    if (!TclIsBareword(*start) || *start == '_') {
	size_t scanned;
	if (TclUCS4Complete(start, numBytes)) {
	if (Tcl_UtfCharComplete(start, numBytes)) {
	    scanned = TclUtfToUCS4(start, &ch);
	} else {
	    char utfBytes[8];

	    memcpy(utfBytes, start, numBytes);
	    utfBytes[numBytes] = '\0';
	    scanned = TclUtfToUCS4(utfBytes, &ch);