procedure DefineProperties(Filer: TFiler); virtual;
virtual void __fastcall DefineProperties(TFiler* Filer);
Provides an interface for a method that reads and writes otherwise unpublished data.
Descendants of TPersistent override DefineProperties to designate a method for storing the object's unpublished data to a stream such as a form file. By default, writing an object to a stream writes the values of all its published properties, and reading the object in reads those values and assigns them to the properties. Objects can also specify methods that read and write data other than published properties by overriding the DefineProperties method.
When overriding DefineProperties, consider including some or all of the following:
A call to the inherited method
Calls to the filer object's DefineProperty method
Calls to the filer object's DefineBinaryProperty method
DefineProperties is virtual, so descendant classes can override it as necessary but are not required to do so.