"The Makefile is half the IDE"
HalfIDE is a proposed standard for the exchange of information between a Makefile, managing all the aspects of a project, and an IDE. A generic IDE can obtain all the project's information from the Makefile, and configure itself accordingly, so that the Makefile is the one and only project file, irrespective of the used IDE.
See the file HalfIDE.htm in the repository for the full protocol specification.