Remove the mention of optional parameters in documentation, as they are marked optional already.

src/basic/Matrix.js

@@ -110,7 +110,7 @@ var Matrix = this.Matrix = Base.extend({
 	 * @name Matrix#scale
 	 * @function
 	 * @param {Number} scale The scaling factor.
-	 * @param {Point} [center] The optional center for the scaling
+	 * @param {Point} [center] The center for the scaling
 	 * transformation.
 	 * @return {Matrix} This affine transform.
 	 */
@@ -121,7 +121,7 @@ var Matrix = this.Matrix = Base.extend({
 	 * @function
 	 * @param {Number} sx The x-axis scaling factor.
 	 * @param {Number} sy The y-axis scaling factor.
-	 * @param {Point} [center] The optional center for the scaling
+	 * @param {Point} [center] The center for the scaling
 	 * transformation.
 	 * @return {Matrix} This affine transform.
 	 */
@@ -203,7 +203,7 @@ var Matrix = this.Matrix = Base.extend({
 	 * @name Matrix#shear
 	 * @function
 	 * @param {Point} point The shear factor in x and y direction.
-	 * @param {Point} [center] The optional center for the shear transformation.
+	 * @param {Point} [center] The center for the shear transformation.
 	 * @return {Matrix} This affine transform.
 	 */
 	/**
@@ -213,7 +213,7 @@ var Matrix = this.Matrix = Base.extend({
 	 * @function
 	 * @param {Number} shx The x shear factor.
 	 * @param {Number} shy The y shear factor.
-	 * @param {Point} [center] The optional center for the shear transformation.
+	 * @param {Point} [center] The center for the shear transformation.
 	 * @return {Matrix} This affine transform.
 	 */
 	shear: function(shx, shy, center) {

src/item/Group.js

@@ -21,8 +21,8 @@ var Group = this.Group = Item.extend({
 	/**
 	 * Creates a new Group item and places it at the top of the active layer.
 	 * 
-	 * @param {Item[]} [children] An optional array of children that will be
-	 * added to the newly created group.
+	 * @param {Item[]} [children] An array of children that will be added to the
+	 * newly created group.
 	 * 
 	 * @example {@paperscript split=true height=200}
 	 * // Create a group containing two paths:

src/item/Layer.js

@@ -23,8 +23,8 @@ var Layer = this.Layer = Group.extend({
 	 * {@link Project#layers} array. The newly created layer will be activated,
 	 * so all newly created items will be placed within it.
 	 * 
-	 * @param {Array} [children] An optional array of items that will be
-	 * added to the newly created layer.
+	 * @param {Array} [children] An array of items that will be added to the 
+	 * newly created layer.
 	 * 
 	 * @example
 	 * var layer = new Layer();

src/path/Path.js

@@ -20,7 +20,7 @@ var Path = this.Path = PathItem.extend({
 	/**
 	 * Creates a new Path item and places it at the top of the active layer.
 	 * 
-	 * @param {Segment[]} [segments] An optional array of segments (or points to be
+	 * @param {Segment[]} [segments] An array of segments (or points to be
 	 * converted to segments) that will be added to the path.
 	 * 
 	 * @example