nv = voice_tb.length,
	vtb = [],
	vn = [],			// voice indexed by range
	sy = cur_sy

	// set the first symbol of each voice
	for (v = 0; v < nv; v++) {
		if (!sy.voices[v])
			continue
		s = voice_tb[v].sym
		vtb[v] = s
		if (!s)
		if (!s || !sy.voices[v])
			continue
		if (s.type == C.STAVES) {	// first symbol by time
			tsfirst = prev = s
			s = s.next
			vtb[v] = s.next
		}
		vtb[v] = s
		vn[sy.voices[v].range] = v
	}
	if (!prev)
		return				// no music
	prev.seqst = true

	// loop on the symbols of all voices