This release of the guidelines embraces the concept of Component Categories which are a part of the OLE specification. In previous versions of this document component categories were loosely referred to as function groups and were used to identify areas of functionality that a container may optionally support, for this version there has been a definition of how component categories work for ActiveX Controls and some fundamental categories are identified. The use of component categories allows the relaxing of some of the previous rules that identified interfaces as being mandatory, and allows greater flexibility for controls to efficiently target certain areas of functionality without having to provide superfluous additional support in order to qualify as a control. This edition of the guidelines also discusses what the presence or absence of an interface means and what to do in that situation.
The remainder of this appendix is divided into four sections. The first discusses guidelines for implementing controls, the second discusses guidelines for implementing control containers, the third discusses component categories, and the fourth discusses general guidelines, relevant to both control and control container developers.