diff --git a/core/block.js b/core/block.js
index ae0295d96..ae1e32363 100644
--- a/core/block.js
+++ b/core/block.js
@@ -279,6 +279,27 @@ Blockly.Block.prototype.colourTertiary_ = null;
  */
 Blockly.Block.prototype.styleName_ = null;
 
+/**
+ * An optional serialization method for defining how to serialize the
+ * mutation state. This must be coupled with defining `domToMutation`.
+ * @type {?function(...):!Element}
+ */
+Blockly.Block.prototype.mutationToDom;
+
+/**
+ * An optional deserialization method for defining how to deserialize the
+ * mutation state. This must be coupled with defining `mutationToDom`.
+ * @type {?function(!Element)}
+ */
+Blockly.Block.prototype.domToMutation;
+
+/**
+ * An optional property for suppressing adding STATEMENT_PREFIX and
+ * STATEMENT_SUFFIX to generated code.
+ * @type {?boolean}
+ */
+Blockly.Block.prototype.suppressPrefixSuffix;
+
 /**
  * Dispose of this block.
  * @param {boolean} healStack If true, then try to heal any gap by connecting
diff --git a/core/block_svg.js b/core/block_svg.js
index 748ddd6ce..ebeb2f852 100644
--- a/core/block_svg.js
+++ b/core/block_svg.js
@@ -208,6 +208,26 @@ Blockly.BlockSvg.TAB_WIDTH = 8;
  */
 Blockly.BlockSvg.START_HAT = false;
 
+/**
+ * An optional method called when a mutator dialog is first opened.
+ * This function must create and initialize a top-level block for the mutator
+ * dialog, and return it. This function should also populate this top-level
+ * block with any sub-blocks which are appropriate. This method must also be
+ * coupled with defining a `compose` method for the default mutation dialog
+ * button and UI to appear.
+ * @type {?function(Blockly.WorkspaceSvg):!Blockly.BlockSvg}
+ */
+Blockly.BlockSvg.prototype.decompose;
+
+/**
+ * An optional method called when a mutator dialog saves its content.
+ * This function is called to modify the original block according to new
+ * settings. This method must also be coupled with defining a `decompose`
+ * method for the default mutation dialog button and UI to appear.
+ * @type {?function(!Blockly.BlockSvg)}
+ */
+Blockly.BlockSvg.prototype.compose;
+
 /**
  * Create and initialize the SVG representation of the block.
  * May be called more than once.