USD output specification

This document defines how MDCX publishes and accepts OpenUSD (typically .usdc) reference designs for modular AI data center containers. It is the first normative engineering spec in the Docs MVP — partners, factories, and future Designer exports should align to these rules.

Status: Public draft v0.1 · 2026-08-10 · Identity via solution code (D-11) · Presentation of 3D on the web follows MEDIA / D-12 (poster first; heavy USD is download-only).

1. Scope

In scope:

• Container-level reference models for published SKUs (e.g. L1240C45SUR150 / alias DC45).
• Packaging for public download (.usdc.zip, .usdc.xz) under /assets/3D/.
• Prim naming, units, up-axis, and LOD tiers so digital-twin and BIM consumers can merge assets reliably.

Out of scope for v0.1:

• Live Omniverse streams, material shading brand kits, or full facility site models.
• Blender source files (AC_3D/, DC45_3D/) — internal only; not deployed to Pages.
• Pricing, BOM cost, or TCO numbers (those live in TCO / CLAIMS).

2. Identity binding

Every published USD package must map to exactly one solution code from the product matrix.

3. Units & coordinate system

4. Prim & asset naming

Use ASCII identifiers; prefer PascalCase for Xforms and snake_case only for files on disk.

• Root prim: /MDCX/<SKU_ID> e.g. /MDCX/L1240C45SUR150
• Alias custom data: mdcx:alias = "DC45", mdcx:code = "L1240C45SUR150", mdcx:line = "LiquidCooling"|"ImmersionCooling"
• Major systems (suggested children): Envelope, Racks or Tanks, Cooling, Power, CableTrays, Clearances
• Instanceable racks/tanks: Rack_01… or Tank_01… with stable indices matching Designer layout order when possible.
• Do not put marketed kW numbers only in mesh names — numbers belong in CLAIMS / matrix; mesh names are structural.

File names on the public CDN may retain legacy labels (DC45-1200KW.usdc) for continuity; the stage metadata must still carry the canonical SKU ID.

5. LOD tiers

If a single file is shipped, treat it as LOD1 and state that in the download caption.

6. Packaging & delivery

• Format: binary USDA crate .usdc preferred for download size; optional .usda sidecar for human review (not required publicly).
• Compression: publish as .usdc.zip or .usdc.xz. Never force multi-hundred-MB raw CAD on first paint (D-12 / PERFORMANCE).
• Textures: either embed or ship a sibling textures/ folder with relative paths; document if textures are omitted (clay / workbench look).
• Web 3D: Sketchfab (or similar) is a presentation surface — poster + click-to-load only. It does not replace the USD package as the interchange truth.
• Version label: include mdcx:usdSpec = "0.1" and an ISO date mdcx:exportedAt in customLayerData when tooling allows.

7. Export checklist

Before publishing a package next to a product page or Docs link:

• SKU ID in stage metadata matches PRODUCT-MATRIX / code used in UI.
• metersPerUnit = 1; up-axis documented; origin documented in one sentence.
• Root path /MDCX/<SKU_ID> (or documented deviation).
• No accidental customer PII, internal paths, or vendor license keys in layer comments.
• File opens in at least one of: usdview, Omniverse, Blender USD, or USD Composer (note which).
• Compressed download under 200 MB preferred; if larger, call out size next to the button.
• Marketing page uses poster-first media; USD is explicit download, not auto-fetched.
• Draft SKUs are not presented as orderable shipped products.

8. Designer / TCO linkage (forward-looking)

When Designers export geometry or an asset manifest:

• Minimum query identity remains ?code=<SKU_ID> (D-14).
• Export manifest JSON should include at least: code, optional alias, usdSpec version, and package filename.
• TCO does not embed USD; post-TCO CTA opens Designer with the same code (D-15).

9. Current public packages

Hosted under /assets/3D/ (see product pages for buttons):

10. Changelog