 Opening devices and querying capabilities in the Linux Kernel video API documentation

Primary source: docs.kernel.org/userspace-api/media/v4l/open.html

Verified locator: Opening and Closing Devices §§1.1.1–1.1.2 and 1.1.6: hardware interfaces, node types/naming and open/close/ioctl. Companion primary page docs.kernel.org/userspace-api/media/v4l/querycap.html §1.2: query supported functions and I/O methods with VIDIOC_QUERYCAP.