> For the complete documentation index, see [llms.txt](https://docs.betterbuilding.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.betterbuilding.io/user-guide/3d-building/specification.md).
# Specification
The specification of a 3D model takes place within the 'Geometry' space. A key concept that applied to specification is the use of tagging across the model for building envelope, spaces and shading.
To begin, left-click you’ll see navigation options appear in the upper ribbon. These include viewer tools and model element categories such as 'Zone', 'Zone Details', 'Wall', 'Floor', 'Door', 'Ceiling', 'Roof', 'Window', 'Skylight', 'Glazed Door', 'Opaque Door', 'Shading' and 'Air Surfaces'. These buttons allow you to identify and select relevant surfaces or zones for further specification.
Under the 'Zone' tab, all zones can be selected at once. Once selected, press Enter on your keyboard to reveal the 'Select Tags' window. For a zone to be available for tagging, a tag must be available for selection. Learn more about [tagging](/user-guide/2d-building/drawing/manage-tags.md). To select multiple zones quickly, hold CTRL and drag your cursor to the right to highlight the desired area.
Within 'Zone Details', you can select individual zones and rename them by updating their title or defining their volume if applicable.
The same selection process applies to walls. Click to select relevant walls across the building, hit Enter, and the Select Tags window will appear. Again, tags must be available in order to apply them. You can select multiple walls by holding CTRL and dragging toward the bottom right of the screen. Press Escape to deselect any walls.
These selection and tagging features work in the same way for Floors, Ceilings, Roofs, Windows, Skylights, Glazed Doors, Opaque Doors, Shading, and Air Surfaces. This consistent approach helps streamline the specification process across all geometry types.
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