diff --git a/go4k/go4k.go b/go4k/go4k.go
index 9e603b5..e8f067e 100644
--- a/go4k/go4k.go
+++ b/go4k/go4k.go
@@ -56,3 +56,200 @@ func Render(synth Synth, buffer []float32) error {
 	}
 	return err
 }
+
+// UnitParameter documents one parameter that an unit takes
+type UnitParameter struct {
+	Name        string // thould be found with this name in the Unit.Parameters map
+	MinValue    int    // minimum value of the parameter, inclusive
+	MaxValue    int    // maximum value of the parameter, inclusive
+	CanSet      bool   // if this parameter can be set before hand i.e. through the gui
+	CanModulate bool   // if this parameter can be modulated i.e. has a port number in "send" unit
+}
+
+// UnitType documents the supported behaviour of one type of unit (oscillator, envelope etc.)
+type UnitType struct {
+	Name           string
+	SupportsStereo bool
+	Parameters     []UnitParameter
+}
+
+// UnitTypes documents all the available unit types and if they support stereo variant
+// and what parameters they take.
+var UnitTypes = []UnitType{
+	{
+		Name:           "add",
+		SupportsStereo: true,
+		Parameters:     []UnitParameter{}},
+	{
+		Name:           "addp",
+		SupportsStereo: true,
+		Parameters:     []UnitParameter{}},
+	{
+		Name:           "pop",
+		SupportsStereo: true,
+		Parameters:     []UnitParameter{}},
+	{
+		Name:           "loadnote",
+		SupportsStereo: true,
+		Parameters:     []UnitParameter{}},
+	{
+		Name:           "mul",
+		SupportsStereo: true,
+		Parameters:     []UnitParameter{}},
+	{
+		Name:           "mulp",
+		SupportsStereo: true,
+		Parameters:     []UnitParameter{}},
+	{
+		Name:           "push",
+		SupportsStereo: true,
+		Parameters:     []UnitParameter{}},
+	{
+		Name:           "xch",
+		SupportsStereo: true,
+		Parameters:     []UnitParameter{}},
+	{
+		Name:           "distort",
+		SupportsStereo: true,
+		Parameters:     []UnitParameter{{Name: "drive", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true}}},
+	{
+		Name:           "hold",
+		SupportsStereo: true,
+		Parameters:     []UnitParameter{{Name: "holdfreq", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true}}},
+	{
+		Name:           "crush",
+		SupportsStereo: true,
+		Parameters:     []UnitParameter{{Name: "resolution", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true}}},
+	{
+		Name:           "gain",
+		SupportsStereo: true,
+		Parameters:     []UnitParameter{{Name: "gain", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true}}},
+	{
+		Name:           "invgain",
+		SupportsStereo: true,
+		Parameters:     []UnitParameter{{Name: "invgain", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true}}},
+	{
+		Name:           "filter",
+		SupportsStereo: true,
+		Parameters: []UnitParameter{
+			{Name: "frequency", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "resonance", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "lowpass", MinValue: 0, MaxValue: 1, CanSet: true, CanModulate: false},
+			{Name: "bandpass", MinValue: 0, MaxValue: 1, CanSet: true, CanModulate: false},
+			{Name: "highpass", MinValue: 0, MaxValue: 1, CanSet: true, CanModulate: false},
+			{Name: "negbandpass", MinValue: 0, MaxValue: 1, CanSet: true, CanModulate: false},
+			{Name: "neghighpass", MinValue: 0, MaxValue: 1, CanSet: true, CanModulate: false}}},
+	{
+		Name:           "clip",
+		SupportsStereo: true,
+		Parameters:     []UnitParameter{}},
+	{
+		Name:           "pan",
+		SupportsStereo: true,
+		Parameters:     []UnitParameter{{Name: "panning", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true}}},
+	{
+		Name:           "delay",
+		SupportsStereo: true,
+		Parameters: []UnitParameter{
+			{Name: "pregain", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "dry", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "feedback", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "damp", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "notetracking", MinValue: 0, MaxValue: 1, CanSet: true, CanModulate: false},
+			{Name: "delay", MinValue: 0, MaxValue: -1, CanSet: false, CanModulate: true},
+		}},
+	{
+		Name:           "compressor",
+		SupportsStereo: true,
+		Parameters: []UnitParameter{
+			{Name: "attack", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "release", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "invgain", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "threshold", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "ratio", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+		}},
+	{
+		Name:           "speed",
+		SupportsStereo: false,
+		Parameters:     []UnitParameter{}},
+	{
+		Name:           "out",
+		SupportsStereo: true,
+		Parameters:     []UnitParameter{{Name: "gain", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true}}},
+	{
+		Name:           "outaux",
+		SupportsStereo: true,
+		Parameters: []UnitParameter{
+			{Name: "outgain", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "auxgain", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+		}},
+	{
+		Name:           "aux",
+		SupportsStereo: true,
+		Parameters: []UnitParameter{
+			{Name: "gain", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "channel", MinValue: 0, MaxValue: 6, CanSet: true, CanModulate: false},
+		}},
+	{
+		Name:           "send",
+		SupportsStereo: true,
+		Parameters: []UnitParameter{
+			{Name: "amount", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "voice", MinValue: -1, MaxValue: 31, CanSet: true, CanModulate: false},
+			{Name: "unit", MinValue: 0, MaxValue: 63, CanSet: true, CanModulate: false},
+			{Name: "port", MinValue: 0, MaxValue: 7, CanSet: true, CanModulate: false},
+		}},
+	{
+		Name:           "envelope",
+		SupportsStereo: true,
+		Parameters: []UnitParameter{
+			{Name: "attack", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "decay", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "sustain", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "release", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "gain", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+		}},
+	{
+		Name:           "noise",
+		SupportsStereo: true,
+		Parameters: []UnitParameter{
+			{Name: "shape", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "gain", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+		}},
+	{
+		Name:           "oscillator",
+		SupportsStereo: true,
+		Parameters: []UnitParameter{
+			{Name: "transpose", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "detune", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "phase", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "color", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "shape", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "gain", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+			{Name: "type", MinValue: int(Sine), MaxValue: int(Sample), CanSet: true, CanModulate: false},
+			{Name: "lfo", MinValue: 0, MaxValue: 1, CanSet: true, CanModulate: false},
+			{Name: "unison", MinValue: 0, MaxValue: 3, CanSet: true, CanModulate: false},
+			{Name: "start", MinValue: 0, MaxValue: 3440659, CanSet: true, CanModulate: false},    // if type is "sample", then the waveform starts at this position
+			{Name: "loopstart", MinValue: 0, MaxValue: 65535, CanSet: true, CanModulate: false},  // if type is "sample", then the loop starts at this position, relative to "start"
+			{Name: "looplength", MinValue: 0, MaxValue: 65535, CanSet: true, CanModulate: false}, // if type is "sample", then the loop length is this i.e. loop ends at "start" + "loopstart" + "looplength"
+		}},
+	{
+		Name:           "loadval",
+		SupportsStereo: true,
+		Parameters: []UnitParameter{
+			{Name: "value", MinValue: 0, MaxValue: 128, CanSet: true, CanModulate: true},
+		}},
+	{
+		Name:           "receive",
+		SupportsStereo: true,
+		Parameters: []UnitParameter{
+			{Name: "left", MinValue: 0, MaxValue: -1, CanSet: false, CanModulate: true},
+			{Name: "right", MinValue: 0, MaxValue: -1, CanSet: false, CanModulate: true},
+		}},
+	{
+		Name:           "in",
+		SupportsStereo: true,
+		Parameters: []UnitParameter{
+			{Name: "channel", MinValue: 0, MaxValue: 6, CanSet: true, CanModulate: false},
+		}},
+}