The NEC: New York category page contains all articles relating to the NEC: New York DLC, released on the 20th March 2018. This includes all locomotives, operators, locations, tutorials and scenarios. Wiki tutorial pages for NEC: New York which will be created at a later date should also be included in this category.
If you believe a page that is related to the NEC: New York DLC is not within this category, you can add it by going to the bottom of the relevant page and clicking on the 'add category' button. Then type in 'NEC: New York' and press the enter key. Then press the 'save' button.