Version 16.5 of the C API has not changed from version 16.
For more information, refer to:
What's New in Version 16.5
Raster .NET | C API | C++ Class Library | JavaScript HTML5
Document .NET | C API | C++ Class Library | JavaScript HTML5
Medical .NET | C API | C++ Class Library | JavaScript HTML5
Multimedia .NET | C API
Medical Web Viewer .NET
.NET
Silverlight
WinRT
WinRT Phone
Java
Android
iOS/macOS
JavaScript HTML5
Multimedia
Medical Web Viewer
C API
C++ Class Library