The following sections show the header and source files for a custom class, AsdkMyClass, which is derived from AcDbObject. This class stores a single integer value, which can be set and queried with its setData() and getData() functions. It also implements dwgInFields(), dwgOutFields(), dxfInFields(), and dxfOutFields() functions for filing. It is written to and read from file, so its source file uses the ACRX_DXF_DEFINE_MEMBERS macro.