Layering standards are guidelines or rules that define how to name, format, and use layers in 2D CAD drafting. These standards help to ensure consistency, compatibility, and efficiency among different drafters, projects, and software. There are industry standards such as the AIA CAD Layer Guidelines, the National CAD Standard, and the ISO 13567. Company standards are specific or customized standards like the US Army Corps of Engineers CAD Standards, the Autodesk Civil 3D Style Guide, and the Bentley MicroStation Standards. Project standards are special or unique standards like the London Crossrail CAD Standards, the Sydney Opera House CAD Standards, and the Burj Khalifa CAD Standards. To follow layering standards, you need to identify the applicable ones for your project or task, obtain or create the standard layer names and properties, apply or assign them to your drawing elements, and check or verify their compliance with the standards. You may need to use various tools in your software such as rename, match, audit, purge, or check to ensure accuracy.