SoTextureCombine(3) on Linux
The text c20ea1015b9c, as Debian 8 (Jessie) shipped it.
The SoTextureCombine class is a node for setting texture combine functions. This node is more or less an exact mapping of the OpenGL ARB_texture_env_combine extension (included in OpenGL in OpenGL v1.3). See http://oss.sgi.com/projects/ogl-sample/registry/ARB/texture_env_combine.txt for more information about this extension.