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 published by MDCX Docs — partners, factories, and future Designer exports should align to these rules.
Status: Public draft v0.1 · 2026-08-10 · Identity via solution code · Presentation of 3D on the web is poster-first; heavy USD is download-only.
1. Scope
In scope:
- Container-level reference models for published SKUs (e.g.
L1240C45SUR150/ alias L1240C45). - 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.
- Authoring-tool source files (Blender, CAD) — the interchange package is the deliverable, not the modelling scene.
- Pricing, BOM cost, or TCO numbers (those live in the TCO tool and the claims registry).
2. Identity binding
Every published USD package must map to exactly one solution code from the product matrix.
| Alias | SKU ID (code) | Public package (examples) |
|---|---|---|
| L1240C45 | L1240C45SUR150 | DC45-1200KW.usdc.zip(legacy filename OK; prefer SKU in metadata) |
| I400C45 | I400C45SUT50 | AC45.usdc.xz |
| L1800C45 | L1800C45DR220 | DLC45-1800KW.usdc.xz |
| L450C20 | L450C20DR150 | DLC20-450KW.usdc.xz |
Rule: Changing IT power, loop topology, UPS flag, size, or density creates a new SKU ID. Do not overwrite the meaning of an existing code. Archive old packages with a dated suffix if needed.
3. Units & coordinate system
| Property | Requirement |
|---|---|
| Linear units | Meters (USD metersPerUnit = 1.0). Document any exception in package README. |
| Up axis | Y-up preferred for Omniverse / common DCC; if Z-up, set stage upAxis and document in metadata. |
| Origin | Container exterior footprint: origin at floor plane, door-end centerline (or documented alternative). Include a World / Root xform that is identity at rest. |
| Forward | +Z out the long axis toward the far end (document if mirrored for a twin container). |
| Scale | 1:1 real world. No “cm” meshes scaled 0.01 without correcting metersPerUnit. |
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 = "L1240C45",mdcx:code = "L1240C45SUR150",mdcx:line = "LiquidCooling"|"ImmersionCooling" - Major systems (suggested children):
Envelope,RacksorTanks,Cooling,Power,CableTrays,Clearances - Instanceable racks/tanks:
Rack_01… orTank_01… with stable indices matching Designer layout order when possible. - Do not put marketed kW numbers only in mesh names — numbers belong in the claims registry / product 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
| LOD | Purpose | Guidance |
|---|---|---|
LOD0 | Marketing / web poster source | Simplified shell + major equipment silhouettes; safe for Sketchfab-class polycounts. |
LOD1 | Design coordination | Racks/tanks, CDU, busways, clearances; default public download when only one file is published. |
LOD2 | Factory / detailed twin | Optional private package; fasteners and non-critical clutter may be included. Not required on mdcx.org. |
If a single file is shipped, treat it as LOD1 and state that in the download caption.
6. Packaging & delivery
- Format: binary USDA crate
.usdcpreferred for download size; optional.usdasidecar for human review (not required publicly). - Compression: publish as
.usdc.zipor.usdc.xz. Never force multi-hundred-MB raw CAD on first paint. - 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 datemdcx:exportedAtin 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 the product matrix / code used in the 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>. - Export manifest JSON should include at least:
code, optionalalias,usdSpecversion, and package filename. - TCO does not embed USD; post-TCO CTA opens Designer with the same
code.
9. Current public packages
Hosted under /assets/3D/ (see product pages for buttons):
| File | Maps to | Notes |
|---|---|---|
DC45-1200KW.usdc.zip | L1240C45 · L1240C45SUR150 | Primary liquid reference · UPS configuration |
DC45-2400KW-GEMINI.usdc.zip | 2× L1240C45 twin layout | Site arrangement example |
DLC45-1800KW.usdc.xz | L1800C45DR220 | Geometry reference · dual loop · compact crate |
DLC45-1800KW.usdc.zip | L1800C45DR220 | Same crate plus logo textures |
DLC20-450KW.usdc.xz | L450C20DR150 | Geometry reference · dual loop |
AC45.usdc.xz | I400C45 · I400C45SUT50 | Immersion reference |
10. Changelog
| Version | Date | Notes |
|---|---|---|
| 0.1 | 2026-08-10 | Initial public draft: units, naming, LOD, packaging, checklist. |
Normative companions:Product matrix · Claims registry(numbers only — not geometry).Questions:yurimeng@mdcx.org