diff --git a/postscript-go/src/cmd/testpostscript.go b/postscript-go/src/cmd/testpostscript.go
index 9835f6e..680805e 100644
--- a/postscript-go/src/cmd/testpostscript.go
+++ b/postscript-go/src/cmd/testpostscript.go
@@ -9,8 +9,8 @@ import (
 	"image"
 	"image/png"
 	"draw2d.googlecode.com/svn/trunk/draw2d/src/pkg/draw2d"
-	//"postscript"
-	"postscript-go.googlecode.com/svn/trunk/postscript-go/src/pkg/postscript"
+	"postscript"
+	//"postscript-go.googlecode.com/svn/trunk/postscript-go/src/pkg/postscript"
 )
 
 
diff --git a/postscript-go/src/pkg/postscript/interpreter.go b/postscript-go/src/pkg/postscript/interpreter.go
index 7c48489..1ddbc26 100644
--- a/postscript-go/src/pkg/postscript/interpreter.go
+++ b/postscript-go/src/pkg/postscript/interpreter.go
@@ -1,3 +1,6 @@
+// Copyright 2010 The postscript-go Authors. All rights reserved.
+// created: 13/12/2010 by Laurent Le Goff
+
 package postscript
 
 import (
@@ -215,6 +218,12 @@ func (interpreter *Interpreter) OperandSize() int {
 	return len(interpreter.valueStack)
 }
 
+func (interpreter *Interpreter) ClearOperands() {
+	interpreter.valueStack = interpreter.valueStack[0:0]
+}
+
+// misc pop
+
 func (interpreter *Interpreter) PopFloat() float {
 	operand := interpreter.Pop()
 	if s, ok := operand.(string); ok {
diff --git a/postscript-go/src/pkg/postscript/operators.go b/postscript-go/src/pkg/postscript/operators.go
index 0b52b0e..2325ed2 100644
--- a/postscript-go/src/pkg/postscript/operators.go
+++ b/postscript-go/src/pkg/postscript/operators.go
@@ -1,3 +1,6 @@
+// Copyright 2010 The postscript-go Authors. All rights reserved.
+// created: 13/12/2010 by Laurent Le Goff
+
 package postscript
 
 type OperatorFunc func(interpreter *Interpreter)
@@ -22,7 +25,6 @@ func restore(interpreter *Interpreter) {
 }
 
 
-
 func initSystemOperators(interpreter *Interpreter) {
 	interpreter.SystemDefine("save", NewOperator(save))
 	interpreter.SystemDefine("restore", NewOperator(restore))
diff --git a/postscript-go/src/pkg/postscript/operators_control.go b/postscript-go/src/pkg/postscript/operators_control.go
index 21e7dfb..0b87b7e 100644
--- a/postscript-go/src/pkg/postscript/operators_control.go
+++ b/postscript-go/src/pkg/postscript/operators_control.go
@@ -1,3 +1,6 @@
+// Copyright 2010 The postscript-go Authors. All rights reserved.
+// created: 13/12/2010 by Laurent Le Goff
+
 package postscript
 
 
@@ -33,9 +36,8 @@ func foroperator(interpreter *Interpreter) {
 }
 
 
-
 func initControlOperators(interpreter *Interpreter) {
 	interpreter.SystemDefine("if", NewOperator(ifoperator))
 	interpreter.SystemDefine("ifelse", NewOperator(ifelse))
 	interpreter.SystemDefine("for", NewOperator(foroperator))
-}
\ No newline at end of file
+}
diff --git a/postscript-go/src/pkg/postscript/operators_dictionary.go b/postscript-go/src/pkg/postscript/operators_dictionary.go
index 5346939..8cd6ecf 100644
--- a/postscript-go/src/pkg/postscript/operators_dictionary.go
+++ b/postscript-go/src/pkg/postscript/operators_dictionary.go
@@ -1,3 +1,6 @@
+// Copyright 2010 The postscript-go Authors. All rights reserved.
+// created: 13/12/2010 by Laurent Le Goff
+
 package postscript
 
 
@@ -87,4 +90,4 @@ func initDictionaryOperators(interpreter *Interpreter) {
 	interpreter.SystemDefine("end", NewOperator(end))
 	interpreter.SystemDefine("dict", NewOperator(dict))
 	interpreter.SystemDefine("where", NewOperator(where))
-}
\ No newline at end of file
+}
diff --git a/postscript-go/src/pkg/postscript/operators_graphics.go b/postscript-go/src/pkg/postscript/operators_graphics.go
index fd977cc..f135ed5 100644
--- a/postscript-go/src/pkg/postscript/operators_graphics.go
+++ b/postscript-go/src/pkg/postscript/operators_graphics.go
@@ -1,3 +1,6 @@
+// Copyright 2010 The postscript-go Authors. All rights reserved.
+// created: 13/12/2010 by Laurent Le Goff
+
 package postscript
 
 import (
diff --git a/postscript-go/src/pkg/postscript/operators_math.go b/postscript-go/src/pkg/postscript/operators_math.go
index 961daed..5267ed2 100644
--- a/postscript-go/src/pkg/postscript/operators_math.go
+++ b/postscript-go/src/pkg/postscript/operators_math.go
@@ -1,82 +1,157 @@
+// Copyright 2010 The postscript-go Authors. All rights reserved.
+// created: 13/12/2010 by Laurent Le Goff
+
+//Arithmetic and Math Operators
 package postscript
 
 import (
 	"math"
+	"rand"
 )
 // begin Primitive Operator implementation
 
-
+//num1  num2 add sum -> Return num1 plus num2
 func add(interpreter *Interpreter) {
-	f2 := interpreter.PopFloat()
-	f1 := interpreter.PopFloat()
-	interpreter.Push(f1 + f2)
+	num2 := interpreter.PopFloat()
+	num1 := interpreter.PopFloat()
+	interpreter.Push(num1 + num2)
 }
-
-func sub(interpreter *Interpreter) {
-	f2 := interpreter.PopFloat()
-	f1 := interpreter.PopFloat()
-	interpreter.Push(f1 - f2)
-}
-
+//num1  num2 div quotient -> Return num1 divided by num2
 func div(interpreter *Interpreter) {
-	f2 := interpreter.PopFloat()
-	f1 := interpreter.PopFloat()
-	interpreter.Push(f1 / f2)
-}
-func mul(interpreter *Interpreter) {
-	f2 := interpreter.PopFloat()
-	f1 := interpreter.PopFloat()
-	interpreter.Push(f1 * f2)
+	num2 := interpreter.PopFloat()
+	num1 := interpreter.PopFloat()
+	interpreter.Push(num1 / num2)
 }
 
+//int1  int2 idiv quotient -> Return int1 divided by int2
+func idiv(interpreter *Interpreter) {
+	int2 := interpreter.PopInt()
+	int1 := interpreter.PopInt()
+	interpreter.Push(float(int1 / int2))
+}
+//int   int mod remainder -> Return remainder after dividing int  by int
+func mod(interpreter *Interpreter) {
+	int2 := interpreter.PopInt()
+	int1 := interpreter.PopInt()
+	interpreter.Push(float(int1 % int2))
+}
+
+//num1  num2 mul product -> Return num1 times num2
+func mul(interpreter *Interpreter) {
+	num2 := interpreter.PopFloat()
+	num1 := interpreter.PopFloat()
+	interpreter.Push(num1 * num2)
+}
+//num1  num2 sub difference -> Return num1 minus num2
+func sub(interpreter *Interpreter) {
+	num2 := interpreter.PopFloat()
+	num1 := interpreter.PopFloat()
+	interpreter.Push(num1 - num2)
+}
+//num1 abs num2 -> Return absolute value of num1
+func abs(interpreter *Interpreter) {
+	f := interpreter.PopFloat()
+	interpreter.Push(float(math.Fabs(float64(f))))
+}
+//num1 neg num2 -> Return negative of num1
+func neg(interpreter *Interpreter) {
+	f := interpreter.PopFloat()
+	interpreter.Push(-f)
+}
+//num1 ceiling num2 -> Return ceiling of num1
+func ceiling(interpreter *Interpreter) {
+	f := interpreter.PopFloat()
+	interpreter.Push(float(int(f + 1)))
+}
+//num1 floor num2 -> Return floor of num1
+func floor(interpreter *Interpreter) {
+	f := interpreter.PopFloat()
+	interpreter.Push(float(math.Floor(float64(f))))
+}
+//num1 round num2 -> Round num1 to nearest integer
+func round(interpreter *Interpreter) {
+	f := interpreter.PopFloat()
+	interpreter.Push(float(int(f + 0.5)))
+}
+//num1 truncate num2 -> Remove fractional part of num1
+func truncate(interpreter *Interpreter) {
+	f := interpreter.PopFloat()
+	interpreter.Push(float(int(f)))
+}
+//num sqrt real -> Return square root of num
 func sqrt(interpreter *Interpreter) {
 	f := interpreter.PopFloat()
 	interpreter.Push(float(math.Sqrt(float64(f))))
 }
-
+//num  den atan angle -> Return arctangent of num/den in degrees
 func atan(interpreter *Interpreter) {
 	den := interpreter.PopFloat()
 	num := interpreter.PopFloat()
 	interpreter.Push(float(math.Atan2(float64(num), float64(den))) * (180.0 / math.Pi))
 }
-
+//angle cos real -> Return cosine of angle degrees
 func cos(interpreter *Interpreter) {
 	a := interpreter.PopFloat()
 	interpreter.Push(float(math.Cos(float64(a))) * (180.0 / math.Pi))
 }
-
+//angle sin real -> Return sine of angle degrees
 func sin(interpreter *Interpreter) {
 	a := interpreter.PopFloat()
 	interpreter.Push(float(math.Sin(float64(a))) * (180.0 / math.Pi))
 }
-
-func neg(interpreter *Interpreter) {
-	f := interpreter.PopFloat()
-	interpreter.Push(-f)
+//base  exponent exp real -> Raise base to exponent power
+func exp(interpreter *Interpreter) {
+	exponent := interpreter.PopFloat()
+	base := interpreter.PopFloat()
+	interpreter.Push(float(math.Pow(float64(base), float64(exponent))))
+}
+//num ln real -> Return natural logarithm (base e)
+func ln(interpreter *Interpreter) {
+	num := interpreter.PopFloat()
+	interpreter.Push(float(math.Log(float64(num))))
+}
+//num log real -> Return common logarithm (base 10)
+func log10(interpreter *Interpreter) {
+	num := interpreter.PopFloat()
+	interpreter.Push(float(math.Log10(float64(num))))
+}
+//– rand int Generate pseudo-random integer
+func randInt(interpreter *Interpreter) {
+	interpreter.Push(rand.Int())
 }
 
-func round(interpreter *Interpreter) {
-	f := interpreter.PopFloat()
-	interpreter.Push(float(int(f + 0.5)))
+var randGenerator *rand.Rand
+//int srand – -> Set random number seed
+func srand(interpreter *Interpreter) {
+	randGenerator = rand.New(rand.NewSource(int64(interpreter.PopInt())))
 }
-
-func abs(interpreter *Interpreter) {
-	f := interpreter.PopFloat()
-	interpreter.Push(float(math.Fabs(float64(f))))
+//– rrand int -> Return random number seed
+func rrand(interpreter *Interpreter) {
+	interpreter.Push(float(randGenerator.Int()))
 }
 
-
-
 func initMathOperators(interpreter *Interpreter) {
 	interpreter.SystemDefine("add", NewOperator(add))
-	interpreter.SystemDefine("sub", NewOperator(sub))
-	interpreter.SystemDefine("mul", NewOperator(mul))
 	interpreter.SystemDefine("div", NewOperator(div))
+	interpreter.SystemDefine("idiv", NewOperator(idiv))
+	interpreter.SystemDefine("mod", NewOperator(mod))
+	interpreter.SystemDefine("mul", NewOperator(mul))
+	interpreter.SystemDefine("sub", NewOperator(sub))
+	interpreter.SystemDefine("abs", NewOperator(abs))
+	interpreter.SystemDefine("neg", NewOperator(neg))
+	interpreter.SystemDefine("ceiling", NewOperator(ceiling))
+	interpreter.SystemDefine("floor", NewOperator(floor))
+	interpreter.SystemDefine("round", NewOperator(round))
+	interpreter.SystemDefine("truncate", NewOperator(truncate))
 	interpreter.SystemDefine("sqrt", NewOperator(sqrt))
+	interpreter.SystemDefine("atan", NewOperator(atan))
 	interpreter.SystemDefine("cos", NewOperator(cos))
 	interpreter.SystemDefine("sin", NewOperator(sin))
-	interpreter.SystemDefine("atan", NewOperator(atan))
-	interpreter.SystemDefine("neg", NewOperator(neg))
-	interpreter.SystemDefine("round", NewOperator(round))
-	interpreter.SystemDefine("abs", NewOperator(abs))
-}
\ No newline at end of file
+	interpreter.SystemDefine("exp", NewOperator(exp))
+	interpreter.SystemDefine("ln", NewOperator(ln))
+	interpreter.SystemDefine("log", NewOperator(log10))
+	interpreter.SystemDefine("rand", NewOperator(randInt))
+	interpreter.SystemDefine("srand", NewOperator(srand))
+	interpreter.SystemDefine("rrand", NewOperator(rrand))
+
+}
diff --git a/postscript-go/src/pkg/postscript/operators_relational.go b/postscript-go/src/pkg/postscript/operators_relational.go
index 7488b53..546a90f 100644
--- a/postscript-go/src/pkg/postscript/operators_relational.go
+++ b/postscript-go/src/pkg/postscript/operators_relational.go
@@ -1,3 +1,6 @@
+// Copyright 2010 The postscript-go Authors. All rights reserved.
+// created: 13/12/2010 by Laurent Le Goff
+
 package postscript
 
 
@@ -16,4 +19,4 @@ func lt(interpreter *Interpreter) {
 func initRelationalOperators(interpreter *Interpreter) {
 	interpreter.SystemDefine("eq", NewOperator(eq))
 	interpreter.SystemDefine("lt", NewOperator(lt))
-}
\ No newline at end of file
+}
diff --git a/postscript-go/src/pkg/postscript/operators_stack.go b/postscript-go/src/pkg/postscript/operators_stack.go
index f7096b8..e55a4ea 100644
--- a/postscript-go/src/pkg/postscript/operators_stack.go
+++ b/postscript-go/src/pkg/postscript/operators_stack.go
@@ -1,18 +1,38 @@
+// Copyright 2010 The postscript-go Authors. All rights reserved.
+// created: 13/12/2010 by Laurent Le Goff
+
+//Operand Stack Manipulation Operators
 package postscript
 
+//any pop – -> Discard top element
 func pop(interpreter *Interpreter) {
 	interpreter.Pop()
 }
-
+//any1  any2 exch any2  any1 -> Exchange top two elements
+func exch(interpreter *Interpreter) {
+	value1 := interpreter.Pop()
+	value2 := interpreter.Pop()
+	interpreter.Push(value1)
+	interpreter.Push(value2)
+}
+//any dup any  any -> Duplicate top element
 func dup(interpreter *Interpreter) {
 	interpreter.Push(interpreter.Peek())
 }
-
+//any1  …  anyn  n copy any1  …  anyn  any1  …  anyn -> Duplicate top n elements
+func copystack(interpreter *Interpreter) {
+	n := interpreter.PopInt()
+	values := interpreter.GetValues(n)
+	for _, value := range values {
+		interpreter.Push(value)
+	}
+}
+//anyn  …  any0  n index anyn …  any0  anyn -> Duplicate arbitrary element
 func index(interpreter *Interpreter) {
 	f := interpreter.PopInt()
 	interpreter.Push(interpreter.Get(int(f)))
 }
-
+//anyn−1  …  any0  n  j roll any(j−1) mod n  …  any0  anyn−1  …  anyj mod n -> Roll n elements up j times
 func roll(interpreter *Interpreter) {
 	j := interpreter.PopInt()
 	n := interpreter.PopInt()
@@ -22,27 +42,47 @@ func roll(interpreter *Interpreter) {
 		interpreter.Push(values[(n+i-j)%n])
 	}
 }
-
-func copystack(interpreter *Interpreter) {
-	n := interpreter.PopInt()
-	values := interpreter.GetValues(n)
-	for _, value := range values {
-		interpreter.Push(value)
+//any1  …  anyn clear -> Discard all elements
+func clear(interpreter *Interpreter) {
+	interpreter.ClearOperands()
+}
+//any1  …  anyn count any1  …  anyn  n -> Count elements on stack
+func count(interpreter *Interpreter) {
+	interpreter.Push(interpreter.OperandSize())
+}
+//Mark
+type Mark struct{}
+//– mark mark -> Push mark on stack
+func mark(interpreter *Interpreter) {
+	interpreter.Push(Mark{})
+}
+//mark  obj 1  …  obj n cleartomark – -> Discard elements down through mark
+func cleartomark(interpreter *Interpreter) {
+	value := interpreter.Pop()
+	for _, ok := value.(Mark); !ok; {
+		value = interpreter.Pop()
 	}
 }
-
-func exch(interpreter *Interpreter) {
-	value1 := interpreter.Pop()
-	value2 := interpreter.Pop()
-	interpreter.Push(value1)
-	interpreter.Push(value2)
+//mark  obj 1  …  obj n counttomark mark  obj 1  …  obj n  n -> Count elements down to mark
+func counttomark(interpreter *Interpreter) {
+	i := 0
+	value := interpreter.Get(i)
+	for _, ok := value.(Mark); !ok; i++ {
+		value = interpreter.Get(i)
+	}
+	interpreter.Push(float(i))
 }
 
-func initStackOperator(interpreter * Interpreter) {
+func initStackOperator(interpreter *Interpreter) {
 	interpreter.SystemDefine("pop", NewOperator(pop))
-	interpreter.SystemDefine("dup", NewOperator(dup))
-	interpreter.SystemDefine("index", NewOperator(index))
-	interpreter.SystemDefine("copy", NewOperator(copystack))
-	interpreter.SystemDefine("roll", NewOperator(roll))
 	interpreter.SystemDefine("exch", NewOperator(exch))
-}
\ No newline at end of file
+	interpreter.SystemDefine("dup", NewOperator(dup))
+	interpreter.SystemDefine("copy", NewOperator(copystack))
+	interpreter.SystemDefine("index", NewOperator(index))
+	interpreter.SystemDefine("roll", NewOperator(roll))
+	interpreter.SystemDefine("clear", NewOperator(clear))
+	interpreter.SystemDefine("count", NewOperator(count))
+	interpreter.SystemDefine("mark", NewOperator(mark))
+	interpreter.SystemDefine("cleartomark", NewOperator(mark))
+	interpreter.SystemDefine("counttomark", NewOperator(mark))
+}
diff --git a/postscript-go/src/pkg/postscript/procedure.go b/postscript-go/src/pkg/postscript/procedure.go
index c17fdee..f14c721 100644
--- a/postscript-go/src/pkg/postscript/procedure.go
+++ b/postscript-go/src/pkg/postscript/procedure.go
@@ -1,3 +1,6 @@
+// Copyright 2010 The postscript-go Authors. All rights reserved.
+// created: 13/12/2010 by Laurent Le Goff
+
 package postscript
 
 type ProcedureDefinition struct {