message: Revise description of pass_by attribute
diff: @@ -562,7 +562,7 @@ specification.
  | arg | type | The type of the argument. Should be a built-in type, ENUM, string, an XML-specified type, or a user-written serializable type. A string type should be used if a text string is the argument. If the type is serial, the port is an untyped serial port that can be connected to any typed port for the purpose of serializing the call. See the Hub pattern in the architectural description document for a usage. |
  | arg | name | Defines the argument name. |
  | arg | size | Specifies the size of the argument if it is of type string. |
  -| arg | pass\_by | Optional. Specifies how the argument should be passed to a handler function. Values can be POINTER or REFERENCE. For a synchronous port handler, the default behavior is to pass by value for primitive values, otherwise by const reference. POINTER causes a pointer to be passed. REFERENCE causes a mutable reference to be passed. For an asynchronous port handler, POINTER causes a pointer to the data to be passed. Otherwise the data itself is serialized, copied into and out of the queue, and deserialized. Use of pointers and mutable references carries the usual responsibility for understanding the scope and lifetime of the memory behind the pointer, as the pointer value may be held by another component past the duration of the port call. |
  +| arg | pass\_by | Optional. Specifies how the argument should be passed to a handler function. Values can be `pointer` or `reference`. For a synchronous port handler, the default behavior (with no `pass_by` attribute) is to pass by value for primitive values, otherwise by const reference. `pass_by="pointer"` causes a pointer to the data to be passed. `pass_by="reference"` causes a mutable reference to be passed. For an asynchronous port handler, `pass_by="pointer"` causes a pointer to the data to be passed. Otherwise the data itself is serialized, copied into and out of the queue, and deserialized. Use of pointers and references carries the usual responsibility for understanding the scope and lifetime of the memory behind the pointer, as the pointer or reference may be held by another component past the duration of the port call. |
  | enum | | Specifies an enumeration when the argument type=ENUM. |
  | enum | name | Enumeration type name. |
  | item | | Specifies a member of the enumeration. |
  