For a thorough description of the module system see the Module System section.
The CMake API can be separated into several categories:
Module APIs module
This category includes functions to find and build VTK modules. A module is a set of related functionality. These are then compiled together into libraries at the “kit” level. Each module may be enabled or disabled individually and its dependencies will be built as needed.
All functions strictly check their arguments. Any unrecognized or invalid values for a function cause errors to be raised.
Internal APIs module-internal
The VTK module system provides some API functions for use by other code which consumes VTK modules (primarily language wrappers). This file documents these APIs. They may start with _vtk_module, but they are intended for use in cases of language wrappers or dealing with trickier third party packages.
Implementation APIs module-impl
These functions are purely internal implementation details. No guarantees are made for them and they may change at any time (including wrapping code calls). Note that these functions are usually very lax in their argument parsing.
Python Wrapping APIs module-wrapping-python
APIs for wrapping modules for Python.
Java Wrapping APIs module-wrapping-java
APIs for wrapping modules for Java.
Support APIs module-support