I view UX as a discipline in that it is rooted in research, methods and instructions. Much the same way Physics or English is rooted. UX is based on the user’s interactions and response, and while UX is made up of UI, IA, IxD and other elements, the instructions given to Design and Development outline goal-oriented interactions and responses, and general real estate assignments. They often do not get into the minutiae of colors (branding), design elements (rounded corners and such), and pageload times which are the responsibility of Design and Development. This, of course, is assuming the UX team is not the same people as the Design and Development team(s), or a one-person project.
UX is the hypothetical blueprint any project is built toward, and then around, and then revisited, iterated upon, over and over again until whatever was originally intended is achieved (or given up on.) The initial UX blueprint should be web industry-specific in that it follows good UX practices and standards. It should be project-specific in that it is driving results for the project’s goals. And it should be audience-specific in that it is based on research and analytics. But, virtually in all cases, it is a set of instructions and guidelines for Design and Development to work out in a physical and dynamic space.
This does not limit the UX team to only handing out wireframes and instructions. They too must understand basic principles of design and development, the C&L of each, as well as trends in the industry (good and bad), and third-party connectivity (APIs.)
Basic skillset: UI patterns, UX testing (including A/B), accessibility, responsive web design, human behaviors, default human interface elements for various browsers and devices (as well as what is considered ‘custom.’)