IDR: Ingress & Durability Rating

IDR (Ingress & Durability Rating) is an independent, unofficial rating system for the dust, grit, water and wear resistance of smartphones, tablets, foldables and other portable electronic devices. It is not affiliated with IEC 60529 (the IP code).

Why IDR exists

Note (informative): IP ratings test a new device’s sealed enclosure while it sits still. Hinges and other moving parts sit outside that enclosure, and in real life a device is worn and moving when dirt and water reach it. A device can carry IP68 while its hinge fills with grit and stops closing.

Core principle

Devices are tested as used: worn first, with moving parts operating.

1. All groups shall be tested on the same unit, in a fixed order: wear (U), then dust (D), then grit (G), then water (W).
2. Every moving part shall be operated during dust, grit and water exposure.
3. Results shall record what happened, including partial damage, not only pass or fail.

The exception for a unit that fails during preconditioning is defined in U: Usage. Test order, unit state and cleaning between groups are defined in Test Conditions. IDR tests are run at one of two test tiers: home or lab.

Status

This specification is Draft v0.3. It is unofficial and incomplete. Codes issued under a draft use version 0 (see Code Format).

Every undefined value is marked [TBD] and listed in Open Issues. Version history is in the Changelog.

Overview

An IDR rating is written in one of two forms.

Every IDRS code shall be derived from a full IDR test report, using the rules in IDRS Short Code. While the specification is a draft, both forms use version 0 (see Code Format).

Reading a full code

Hypothetical example: IDR1 U2 D3 G2rC W52E

The grammar is defined in Code Format and the letters in Effect Letters.

Reading a short code

Hypothetical example: IDRS1 315, read “I-D-R-S one, three-one-five”. It is derived from the same hypothetical test as the full code above.

The full derivation is shown in the worked example.

Definitions

Every term below is used with exactly this meaning throughout the specification.

Code Format

This chapter defines the grammar of the full IDR code. The short code is defined in IDRS Short Code.

Grammar

IDR{version}{tier marker} U… D… G… W…

Each group segment is written as:

group letter + level digit(s) + effect letters (lowercase, optional) + failure letter (uppercase, optional)

Version prefix

1. The code shall begin with IDR followed immediately by the major spec version, with no space (IDR1).
2. Codes from different major versions are not comparable.
3. While this specification is a draft (version 0.x), codes shall use major version 0: IDR0 and IDR0*.

Note (informative): Examples in this specification use IDR1 to show the format codes will take under version 1. Draft-era IDR0 codes are not comparable with version 1 codes.

Home-tier marker

1. Home-tier codes shall carry * immediately after the version: IDR1*.
2. Lab-tier codes shall carry no marker: IDR1.
3. A code marked * is never equivalent to a lab-tier code.
4. In Markdown and similar markup, a code shall be written in code formatting (`IDR1* …`) or with the * escaped (IDR1\*), so that it is not read as emphasis.

The tiers are defined in Test Tiers.

Groups

1. A full code shall contain all four groups, in the order U, D, G, W.
2. Groups shall be separated by single spaces.

Untested groups

1. X shall replace the level digit(s) of a group that was not tested (GX).
2. An untested group shall carry no letters.

Effect letters

1. Effect letters shall be lowercase and taken only from the closed list in Effect Letters.
2. Every effect present at the rated level shall be recorded, in alphabetical order.
3. i shall be used only when no other effect is present.
4. A group with no effect letters had no ingress and no effect at the rated level.

Failure letter

1. At most one failure letter shall be written, after the effect letters.
2. The failure letter names the failure at the next level above the rated level (for W, the next step on the W ladder).
3. If several failures appear at once, the most severe shall be used, in this priority order:

The priority of the water letters F and M is [TBD].

Absent failure letter

No failure letter means no failure was reached: either the top of the scale was passed, or testing stopped first. Stopping first is normal for home-tier tests.

Effect Letters

1. Testers shall use only the letters in this list.
2. A lowercase letter means the effect was observed and is within tolerance.
3. An uppercase letter means the effect caused failure.
4. The thresholds apply to every group the letter is listed for.

How letters are placed in a code is defined in Code Format. How each effect is measured is defined in Measurements.

Closed list

Note (informative): All thresholds are provisional and will be adjusted once real devices have been tested. See Open Issues.

Note (informative): Medium resting on the outer surface or in the outer lip of a seam is not ingress. Sprinkled medium always lands there, so counting it would put i on nearly every test.

Note (informative): Rough motion uses r rather than g because an uppercase G would collide with the G group letter.

IDRS Short Code

Format

IDRS{version} {dust}{grit}{water}

1. The short code shall be IDRS, the major spec version (as in the full code), a space, then three digits in the fixed order dust, grit, water.
2. A group that was not tested shall be shown as X.

While this specification is a draft, short codes use version 0 (IDRS0).

Eligibility

1. An IDRS code shall be issued only from a lab-tier test. Home-tier tests cannot produce one (see Test Tiers).
2. An IDRS code shall be derived only from units at or above the standard wear level. These are the eligible units. Units written UX are not eligible.
3. If no unit is eligible, no IDRS code shall be issued. The full codes can still be published.
4. An IDRS code is valid only when the full IDR codes and the test report are published alongside it.

Derivation rules

1. Never better than the full result. When a rule is unclear, round down.
2. Derived from the report, not the code. Each digit shall be worked out from the per-level and per-step results in the test report.
3. Dust and grit digits: the highest level passed with no effect letters other than i.
4. Water digit: the deepest depth tier whose time tier 2 step was passed with no effect letters other than i. If there is none, the digit is 0.
5. Multiple units: the lowest digit across all eligible units shall be used.
6. Enclosure breach found at teardown: a unit shall not contribute a digit for a group its breach is attributed to. If no eligible unit remains for that group, its digit is 0.

Note (informative): Rule 2 exists because the full code only records effects at the rated level. Effects at lower levels, which decide the IDRS digit, appear only in the report.

Worked example (hypothetical)

One unit is shown. It was preconditioned to U2, assumed here to be the standard wear level.

Full code: IDR1 U2 D3 G2rC W52E Short code: IDRS1 315

Note (informative): The grit digit drops from 2 to 1 because the level-2 pass came with rough motion (r).

U: Usage

What U tests

U applies simulated wear to a unit before all other groups are tested (see the core principle).

Scale

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

Real-wear units are written UX until a wear metric maps real wear onto U levels [TBD].

Note (informative): UX uses the existing “not tested” marker: no preconditioning was performed, and the unit’s real condition is in the report. Most home-tier units are U0 or UX.

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

1. The digit is the highest wear level completed.
2. Effect letters record effects seen after wear. Example (hypothetical): U2h means hold force had dropped after level-2 wear.
3. 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.

D and G: Particulate Testing

This chapter defines the scale, dose, procedure and grading shared by the D (dust) and G (grit) groups. The two groups differ only in their test medium and full dose, which are defined in their own chapters.

Exposure area

A = sum of (length × width) of the largest face of each rigid section, in cm²

Note (informative): Dose scales with exposure area, not mass. Particles get in through surfaces, seams and moving parts, so a dense device and a light device of the same size have the same exposure. Devices with hinges receive a larger dose automatically, in proportion to their extra surfaces and seams.

Dose

Dose (g) = (A ÷ 100) × F × p

1. Every dose shall be weighed. The weighed mass is the dose.
2. Volume measures may be used as rough guidance only (see Volume Conversions).

Note (informative): Powders pack differently depending on the product and how they are scooped. One tablespoon (15 mL) of dry sand weighs roughly 23 g, but a tablespoon of fine powder can weigh anywhere from about 5 to 15 g. This is why doses are weighed rather than measured by volume.

Example doses (informative)

Scale

Levels are cumulative: each level adds more medium and more cycles on top of the previous level, with no cleaning in between.

For each level, the dose increment shall be the difference between that level’s cumulative dose and the previous level’s, and the cycles run shall be the difference between their cumulative cycles.

Note (informative): Cumulative levels reproduce debris building up over time.

Cycle

One cycle means operating every moving part through its full range once, at about one cycle every 2 seconds:

Procedure

Procedure steps are written in the imperative and are requirements unless they say otherwise. Equipment is listed in Kits and safety requirements in Safety.

Before testing

1. Confirm the unit meets Test Conditions, including its baseline for this group.
2. Measure the exposure area and calculate the dose for every level.
3. Home tier: the tester may choose a maximum level in advance.

Each level

1. Weigh the dose increment for this level.
2. Place the unit on the raised rack inside the bin, in its most open state (hinged devices fully open; slab devices front face up). The rack shall hold the unit clear of medium that has fallen to the bin floor.
3. Apply half the increment, sprinkled evenly from about 10 cm above. The medium may be shaken through the #20 sieve to give an even spread.
4. Brush each seam, hinge line and port opening with 5 light strokes.
5. Run half the level’s cycles.
6. Turn the unit over on the rack (hinged devices: close it). Apply the other half of the increment to the exposed faces, edges and ports, brush, and run the remaining cycles.
7. Shed loose material: hold the unit edge-down and tap it 3 times on each long edge onto a folded towel. Do not blow or wipe the seams at this stage.
8. Measure every applicable effect (see Measurements) and record the results.
9. Grade the level (see Grading) and decide whether to continue (see Stop rules).

Note (informative): Without the rack, a unit turned over in step 6 would lie in the medium that fell during the first half, so its real dose would depend on the size of the bin.

Stop rules

Note (informative): Home testers stop at the first sign of degradation to give the device the best chance of surviving.

After testing

Grading

1. A level is passed if no uppercase effect appeared after it.
2. The digit is the highest level passed (0 if level 1 failed).
3. Effect letters and the failure letter shall be written per Code Format, including the failure-letter priority order and the meaning of an absent failure letter.
4. Enclosure breaches found at teardown are handled per Test Tiers.

Examples (hypothetical)

D: Dust

What D tests

D tests sealing: whether seals keep fine particles out of the device.

Threat: fine particles slipping through seals into the device.

Medium

The D medium is defined in Test Media.

Lab-tier D tests shall use a UV tracer. Tracer equipment is listed in Kits and its preparation in Test Media.

Note (informative): The tracer lets teardown show where dust got in, and tells D debris apart from G debris (see attributing an enclosure breach).

Full dose

Scale, procedure and grading

D uses the shared scale, dose formula, procedure and grading in D and G: Particulate Testing.

G: Grit

What G tests

G tests mechanism tolerance: whether moving parts keep working with debris inside them.

Threat: coarse particles jamming or grinding moving parts.

Medium

The G medium is defined in Test Media.

Full dose

Scale, procedure and grading

G uses the shared scale, dose formula, procedure and grading in D and G: Particulate Testing.

W: Water

What W tests

W tests resistance to fresh water at increasing depth and duration, with moving parts operating.

Medium

1. W tests shall use fresh, potable tap water.
2. Distilled, deionized, salt and pool (chlorinated) water shall not be used.
3. Water temperature shall be recorded at each step.

Note (informative): Distilled and deionized water conduct electricity poorly and can hide electrical faults that tap water would cause. Salt and pool water are planned as future groups.

Scale

W is graded on two scales.

Ladder

A step is one exposure at one depth tier for one time tier. Steps run in this order:

1. Each step shall be a separate exposure.
2. Time tiers 3 and 4 shall be run only at the deepest depth tier tested, and never at depth tier 1.

Note (informative): Steps are cumulative, like D and G levels: each exposure adds to the ones before it. Running time tier 2 at every depth lets the IDRS water digit be derived from the report.

Stop rules

Procedure

Procedure steps are written in the imperative and are requirements unless they say otherwise.

Before testing

1. Confirm the unit meets Test Conditions, including its W baseline.
2. Home tier: the tester may choose a maximum depth tier and a maximum time tier in advance. Only depth tiers the tester can physically perform may be claimed.

Each step

1. Expose the unit.
   • Depth tier 1: spray or splash, by a method [TBD].
   • Depth tiers 2–5: immerse the unit with its lowest point at the tier’s depth. The lab tier may instead use a pressure vessel at the hydrostatic pressure of fresh water at that depth.
2. Cycle moving parts during the exposure, [TBD] cycles per step (see cycle). If the unit cannot be reached (for example, in a pressure vessel), run the cycles immediately before and immediately after the exposure, and record this in the report.
3. Hold for the time tier’s duration.
4. Remove and dry the exterior: shake out water and wipe with a lint-free cloth. Do not use heat or compressed air.
5. Measure every applicable effect (see Measurements). Measure m after the drying period [TBD].
6. Grade the step (see Grading) and decide whether to continue (see Stop rules).

After testing

Grading

1. W shall be written W{depth}{time}.
2. A step is passed if no uppercase effect appeared after it.
3. The depth digit is the deepest depth tier whose time tier 1 step was passed.
4. The time digit is the longest time tier passed at that depth tier.
5. A unit that fails the first step shall be written W0 with its failure letter and no time digit.
6. Effect letters record the effects present after the rated step, per Code Format.
7. The failure letter names the failure at the next step on the ladder, per Code Format.

Examples (hypothetical)

Water-specific effects

Thresholds for both are in Effect Letters.

Test Tiers

IDR has two test tiers:

• Home: for an individual testing one device they intend to keep.
• Lab: for testers who can sacrifice and tear down two or more devices.

Note (informative): Home results are useful for comparing devices and spotting weak points, but they cannot confirm sealing. This is why the * marks them as never equivalent to lab results.

Lab tier: teardown

After the last group tested, every lab-tier unit shall be torn down as follows.

1. Tear down the unit. Inspect each sealed compartment for debris and liquid, and photograph it under UV light.
2. Record the state of every liquid contact indicator the device has.
3. Inspect hinge and mechanism internals for debris, scoring and damaged parts. Photograph and describe them.
4. Record any enclosure breach with its location, and attribute it (see below).

The exterior UV photographs taken after D (see Between-group cleaning) form part of the teardown record.

Attributing an enclosure breach

1. Every group whose evidence is found shall be attributed.
2. If the evidence does not identify a group, every group tested on that unit shall be attributed.
3. Each attributed group’s result for that unit shall be marked unverified in the report. The code digit stands as tested.
4. No IDRS digit for an attributed group shall be taken from that unit (see IDRS Short Code).

Note (informative): A teardown cannot show at which level or step a breach happened, which is why the result is marked unverified rather than regraded. Water can also carry D medium further into the device, so a D breach found after W may have been helped by the water. See Open Issues.

Test Conditions

This chapter defines the conditions that apply to every group: test order, the unit’s state, baselines, and cleaning between groups.

Test order

1. The groups tested on a unit shall be tested in the order U, D, G, W (see the core principle).
2. A group that is skipped is written X (see Code Format). The remaining groups are still tested in order.
3. The report shall state which groups were skipped.

Note (informative): A skipped group changes the unit’s condition for the groups after it. For example (hypothetical), a unit tested DX G5 reached G with less prior exposure than one tested D9 G5.

Unit state

1. Before the first group, record the unit’s condition (age, visible wear, prior repairs) and remove cases, covers and screen protectors.
2. The unit shall be powered on, with the screen on, during every exposure. The screen timeout should be set to its longest value, and auto-lock disabled where the device allows it.
3. Button presses during cycling may change the unit’s state (screen off, locked, an app opened). Before each measurement, the unit shall be woken, unlocked and returned to its home screen.
4. The unit shall have enough charge to stay powered on through each group. Charging restrictions are in Safety.
5. Temperature and humidity shall be recorded at the start of each group.

Note (informative): A powered unit shows electrical faults (E), touch faults (s) and button faults (b) as they happen.

Baselines

1. Baseline measurements (see Measurements) shall be taken immediately before each group’s exposure begins, after any between-group cleaning.
2. Thresholds in Effect Letters compare against that group’s baseline.
3. The report shall also record each measurement’s change from the first baseline taken on the unit.

Note (informative): Per-group baselines stop damage from an earlier group being counted again in a later one. The comparison with the first baseline keeps the cumulative picture.

Between-group cleaning

This procedure applies at both tiers after D and after G. At the home tier it also applies after the last group tested, as recovery cleaning. Drying after W is defined in W: Water.

1. Lab tier, after D only: photograph every face, seam and port under UV light before cleaning.
2. Tap out loose material on every edge.
3. Use the hand air blower across seams, grilles and ports, not straight into them, while operating moving parts slowly to work debris out.
4. Brush seams and ports gently with the soft brush.
5. Clean the screen with a dry lint-free cloth.
6. Do not use liquids or canned air.
7. Measure every applicable effect and record the results. Between groups, these are the next group’s baseline. After the last group, they are the home tier’s after-recovery measurements.

Note (informative): The UV photographs keep the evidence of where traced dust reached before cleaning removes it. Canned air is high pressure and can drive debris deeper. An effect that remains after cleaning is likely permanent, which is useful to report.

Measurements

This chapter defines how each effect is measured. Thresholds for lowercase and uppercase letters are in Effect Letters.

1. Every applicable measurement shall be taken at each group’s baseline and after each level or step.
2. An effect that does not apply to a unit (for example, closure gap on a slab phone) shall be recorded as N/A.

Methods

Judgement calls

The b, r and s thresholds depend partly on the tester’s judgement.

1. The baseline and per-level or per-step photos, audio and video for these effects shall be kept with the report, so others can review each call.
2. Each call should be confirmed by a second person where one is available. The report shall state whether it was.
3. For r, the tester may compare the sound level of each recording with the baseline recording using a sound-level meter app. An objective r threshold is [TBD].

Reporting

Report contents

A test report shall contain the items below for every group tested.

All groups

D and G

W

U

Report contents for U are [TBD], pending the U procedure. A report template is also [TBD].

An IDRS code is valid only when the report is published alongside it (see IDRS Short Code).

Combining multiple units

1. A lab report shall publish each unit’s full code alongside its wear condition.
2. The headline code is the full code of the eligible unit (see IDRS Short Code) with the lowest wear level.
3. If several eligible units share that wear level, the headline code is the one with the lowest digits, compared in the order D, G, W.
4. If no unit is eligible, no headline code is published. Each unit’s full code is still published.
5. The IDRS code is derived from all eligible units per IDRS Short Code.

Note (informative): The headline code represents a unit in standard condition. The IDRS code takes the lowest digit across all eligible units, so it never claims more than the most worn eligible unit achieved. This rule may be revisited once the U chapter defines a wear metric.

Safety

Media

1. A respirator (N95 minimum) and safety glasses shall be worn whenever handling, sieving or applying either test medium. A P100 respirator should be used.
2. Sand shall be sieved and agitated outdoors or with strong ventilation. This applies to all sand, including “washed” play sand.
3. Silica flour, ground glass and other fine abrasive powders shall not be used in the home kit.

Note (informative): Sand contains crystalline silica. Sieving and agitating it releases respirable silica dust, which causes silicosis.

UV light

1. The UV flashlight shall not be shone into anyone’s eyes.
2. Safety glasses worn under UV light should be UV-rated.

Device

1. The unit shall be backed up before testing.
2. If the unit becomes hot, swells, smells or smokes, testing shall stop immediately and the unit shall be moved outdoors onto a non-flammable surface.
3. The unit shall not be charged during exposure. After water exposure, it shall not be charged until the drying period [TBD] has passed.

Note (informative): Charging through a wet port can corrode its contacts or short the device.

Note (informative): For home testers, the procedure aims to keep the device working, but there is no guarantee. Some debris may stay in the device permanently, and deliberately contaminating a device may void its warranty.

Pressure vessels

1. A pressure vessel used for W shall be rated for the pressure applied.

Kits

Home kit

Note (informative): A scale is required because volume measures are not accurate enough. Humidity is recorded because it affects how powders clump.

Lab kit

Everything in the home kit, plus:

Test Media

D and G media

Note (informative): D and G use different materials because sealing (D) depends mainly on particle size, so a soft, low-hazard mineral like calcium carbonate is a reasonable home substitute. Mechanism damage (G) depends on particle hardness as well, so G uses real quartz sand.

Carbonate check

Home-kit sand that is not sold as silica sand shall pass this check before use.

1. Drop a pinch of the sand into white vinegar.
2. Watch for a steady stream of bubbles.
3. Sand that produces a steady stream of bubbles shall not be used.

Note (informative): Some play sand is crushed limestone, marble or coral, which is calcium carbonate. It fizzes in vinegar and is much softer than quartz, so it would understate grit damage.

Ultrafine medium

A home tester who wants an ultrafine D medium (< 10 µm) shall buy a graded powder and record its datasheet particle size in the report.

Note (informative): Particles finer than 75 µm cannot be produced with hand sieves.

UV tracer

When a UV tracer is used, about 1% UV-fluorescent pigment by mass shall be mixed into the D medium. It is optional at the home tier and required for lab-tier D tests (see D: Dust).

The water used for W is defined in W: Water. Handling safety for all media is in Safety.

Volume Conversions

Note (informative): This whole appendix is informative. The weighed mass is always the dose (see Dose).

For a typical phone at level 9, that is roughly 5 tablespoons of sand for G, and anywhere from 2 to 6 tablespoons of powder for D. The width of that range is why doses are weighed.

Open Issues

Design questions

1. Timing of enclosure breaches. Teardown shows that dust or water got into a sealed compartment, but not at which level or step. Water can also carry D medium further in. One possible fix is a separate verification unit taken straight to a claimed level and then torn down. See Test Tiers.
2. Combining multiple units. An interim rule (per-unit codes plus a headline code) is defined in Reporting. Revisit it once U: Usage defines a wear metric.
3. Calibration. The doses and thresholds are starting points. After testing a range of devices, adjust them so real devices spread across levels 1–9. If almost everything scores 0 or 9, the scale is set wrong.
4. Home vs lab equivalence. Test the same model with both kits and compare.
5. Cycling consistency. Hand cycling varies between testers. A motorized cycling rig with a fixed speed and range would make results more repeatable.
6. Real-wear units. Units with real wear are written UX and cannot contribute to IDRS until a wear metric maps real wear onto U levels. See U: Usage.
7. Objective rough-motion threshold. r currently relies on what is heard or felt. A sound-level comparison against the baseline recording could replace it. See Measurements.
8. Definitions to confirm. The definitions of sealed compartment, rigid section and tolerance were written during the v0.2 restructure, not taken from the drafts, and need the author’s confirmation. See Definitions.
9. Future water groups. Salt and pool (chlorinated) water are planned as future groups.

[TBD] register

Changelog

v0.3 (2026-11-01)

Resolved contradictions and gaps found in a review of v0.2.

Structure

• Added Test Conditions: test order, unit state, per-group baselines and between-group cleaning. Home recovery cleaning moved there from Test Tiers and now also applies between groups at both tiers.
• Enclosure-breach handling moved from D: Dust to Test Tiers, because breaches can now be attributed to D, G or W.

Substantive changes

• Teardown happens once, after the last group tested, so lab units can complete W. Lab units are photographed under UV after D, before cleaning.
• Breach attribution: breaches are attributed to D (fluorescent debris), G (coarse grains) or W (liquid, corrosion, liquid contact indicators). Attributed results are marked unverified, and those units give no IDRS digit for that group; if none remain, the digit is 0. This replaces the [TBD] for how the IDRS dust digit is written.
• Lab results: every unit’s full code is published, plus a headline code from the least-worn eligible unit.
• IDRS: only units at or above the standard wear level are eligible, and rule 5 takes the lowest digit across eligible units only. This fixes the conflict with the eligibility rule. “Passed cleanly” for the water digit now means no effect letters other than i.
• Versions: draft-era codes use major version 0 (IDR0, IDR0*, IDRS0). The short code now carries the version (IDRS1 315).
• Markup: codes in Markdown must be in code formatting or have the * escaped.
• Absent failure letter: one rule for every group (top passed, or testing stopped first).
• U digit: new units are U0, preconditioned units take their wear level, and real-wear units are UX. The standard wear level is now defined in U: Usage.
• Ingress (i) now means medium or water inside an opening, below the outer surface. Medium on the outer surface no longer counts.
• Thresholds now apply to every group the letter is listed for, not only D and G.
• Unit state: units are powered on with the screen on during exposure, and are not charged during exposure or while wet.
• Per-group baselines: thresholds compare against a baseline taken before each group. Change from the first baseline is also reported.
• Rack: during D and G, the unit sits on a raised rack clear of fallen medium.
• G medium: home sand must be silica, checked with a vinegar carbonate check.
• W: defined the ladder (time tiers 1 and 2 at each depth, then 3 and 4 at the deepest), stop rules, grading, failure letter, the water type (tap; no distilled, deionized, salt or pool water), immersion depth, pressure-vessel option, cycling and drying. Depth tier 1 is not run at time tiers 3 and 4. The example code became W52E, because a failure at 1 h must carry a failure letter.
• Measurements: recordings for b, r and s are kept for review, with optional second-person confirmation.
• Safety: added UV, charging and pressure-vessel requirements.
• Reporting: added W items, unit state, skipped groups, judgement confirmation and teardown attribution.

v0.2 (2026-11-01)

Restructured the specification as an mdBook, merging the Overview draft (v0.1) and the Dust and Grit test documentation (draft v0.2). Where the two conflicted, the Dust and Grit documentation was followed.

Structure

• Split both drafts into one chapter per subject: the rating, test groups, testing, equipment and appendices.
• Added Definitions.
• Moved rationale into informative notes and wrote requirements in shall/should/may form without changing their meaning.
• Collected every [TBD] and unresolved question in Open Issues.

Substantive changes from v0.1

• D and G levels are now 0–9. The v0.1 dose table (levels 0–3) was removed.
• D and G now have a defined exposure area, dose formula, cycle definition, procedure, stop rules and grading.
• The grinding letter g was renamed r (rough motion), to avoid uppercase G colliding with the G group letter.
• The G medium is now the sieved sand blend, replacing “ISO 12103-1 A4 plus 150–850 µm sand”. The D medium gained a home-kit option (calcium carbonate).
• Added home and lab test tiers. Home-tier codes use the IDR1* prefix.
• Effect letters: merged into one closed list with provisional thresholds for D and G. The failure-letter priority order (E, S, C, R, H, B) was added.
• A digit below 9 with no failure letter (D and G) now means testing was stopped before failure, replacing “failure letter omitted only if the top level was passed”.
• IDRS is now lab tier only. For multiple units, the lowest digit is used until the U chapter defines otherwise.
• The example code was updated to IDR1 U2 D3 G2rC W52; its D and G meanings were reinterpreted on the 0–9 scale.
• Added the safety requirements, kits, test media and report checklist.

v0.1

Initial Overview draft: code format, U and W groups, D and G on a 0–3 dose scale, effect letters and the IDRS short code.