ACC-003
Hard constraint
layer: sentence
No nested double negatives
IF a double negative or negative inside another condition obscures polarity, THEN rewrite with one explicit positive or negative operation ELSE retain a necessary legal distinction with explanation.
Why the rule exists
Polarity nesting raises the chance of reversing the intended action.
Condition
The rule fires when this evaluates true. Paths marked below must be present in the fact base; the engine reports the rest rather than guessing them.
- sentence.polarity_nesting_depth gt 1
Facts this rule reads
| Path | Source |
|---|---|
sentence.polarity_nesting_depth |
Derived from text |
Then
- rewrite — target
single_explicit_polarity - explain — target
sentence
Else
- retain — target
current_text, No triggering condition is present.
LAKA
- Smallest sufficient intervention
- Yes
- Primary axes
Sources
-
Making Content Usable for People with Cognitive and Learning Disabilities — W3C
link
Clear words, simple voice and tense, explicit instructions, and supportive structure.
The raw rule record
Verbatim from 17-accessibility-rules.json. Also available at /v1/rules/ACC-003.
{
"id": "ACC-003",
"name": "No nested double negatives",
"domain": "accessibility",
"layer": "sentence",
"strength": "hard_constraint",
"human_logic": "IF a double negative or negative inside another condition obscures polarity, THEN rewrite with one explicit positive or negative operation ELSE retain a necessary legal distinction with explanation.",
"when": {
"path": "sentence.polarity_nesting_depth",
"operator": "gt",
"value": 1
},
"then": [
{
"action": "rewrite",
"target": "single_explicit_polarity"
},
{
"action": "explain",
"target": "sentence",
"when": "legal_distinction_required"
}
],
"else": [
{
"action": "retain",
"target": "current_text",
"reason": "No triggering condition is present."
}
],
"unless": [],
"because": "Polarity nesting raises the chance of reversing the intended action.",
"diagnostics": [],
"examples": {},
"source_ids": [
"WEB-006"
],
"laka": {
"smallest_sufficient_intervention": true,
"primary_axes": [
"scope",
"depth",
"magnitude",
"reversibility"
]
}
}Other accessibility rules
- ACC-001 Use clear words for the actual audience IF a simpler word is equally accurate, respectful, and familiar, THEN use it ELSE retain the necessary precise term with support. Context default
- ACC-002 Simple tense and voice when possible IF present active construction expresses the real time and actor, THEN prefer it ELSE use the tense and voice accuracy requires. Context default
- ACC-004 Separate each instruction IF multiple actions appear in one block and can be completed separately, THEN make each a separate step ELSE retain a single compound action. Context default
- ACC-005 Explain implied meaning when consequential IF humor, irony, metaphor, convention, or context carries a consequential instruction or conclusion, THEN state the literal meaning too ELSE retain. Hard constraint
- ACC-006 Headings and labels are unique and descriptive IF repeated or vague headings prevent out-of-context identification, THEN rename them by topic or task ELSE retain. Hard constraint
- ACC-007 Text alternatives convey function or information IF meaningful non-text content appears, THEN provide a concise equivalent of its purpose and relevant information; IF decorative, mark it ignorable ELSE block release. Hard constraint
- ACC-008 Do not encode meaning by color alone IF color distinguishes status, category, instruction, or error, THEN add text, shape, icon, pattern, or position with an accessible label ELSE retain. Hard constraint
- ACC-009 Avoid directional text without structural anchor IF instructions say above, below, left, right, or color-only location and layout can reflow, THEN name the control, section, or landmark ELSE retain stable spatial instruction. Hard constraint