Apart from appearing in one of the examples, the wip.h header is not even mentioned anywhere in the text of the v5.10 WIP User Manual!
Open AT® IP Connectivity Development Guide (WIPlib v5.10)
Revision: 003
Date: December 15, 2008
all the parts do have a chapter “required header file”
WipLib 5.20
rev 008
They do - but it’s a separate header for each chapter.
There is no mention that the one wip.h file is available to include all the others.