U: Usage
What U tests
U applies simulated wear to a unit before all other groups are tested (see the core principle).
Scale
| Level | Meaning |
|---|---|
| U0 | Tested new, no preconditioning |
| U1 to U4 | Increasing wear: fold cycles, button presses, port insertions, drops. Cycle counts per level [TBD] |
Standard wear level
The standard wear level is U2 [TBD]. IDRS codes are issued only from units at or above it (see IDRS Short Code).
U digit by unit condition
| Unit condition | U digit |
|---|---|
| New, not preconditioned | U0 |
| Preconditioned with simulated wear | The highest wear level completed (U1–U4) |
| Used (real wear), not preconditioned | UX, with the unit’s condition recorded in the report |
Real-wear units are written UX until a wear metric maps real wear onto U levels [TBD].
Note (informative):
UXuses the existing “not tested” marker: no preconditioning was performed, and the unit’s real condition is in the report. Most home-tier units areU0orUX.
Procedure
[TBD]. This includes how a unit’s wear condition is measured, which the lab tier uses to spread units across wear (see Test Tiers).
Grading
- The digit is the highest wear level completed.
- Effect letters record effects seen after wear. Example (hypothetical):
U2hmeans hold force had dropped after level-2 wear. - If a unit fails during preconditioning, the failure letter records why. The remaining groups shall then be tested on a fresh unit preconditioned to the last completed level.
How a lab test with several units is published is defined in Reporting.