warning · Section 8: Punctuation and word count
Rule 8.4: In a vertical list, a colon has the effect of a period on word count
When a colon introduces a vertical list, it acts like a period: the lead-in text before the colon must not exceed the applicable sentence word-count limit (20 words for a procedural sentence, 25 words for a descriptive sentence), and each item after the colon is counted as a new, independent sentence subject to that same limit.
What a checker looks for
Usually a deviation, and context can excuse it.
- Count the words before a colon that introduces a vertical list and flag it if it exceeds 20 words (procedural sentence) or 25 words (descriptive sentence).
- Count the words of each item that follows the colon in the vertical list as its own sentence, and flag any single item that exceeds 20 words (procedural) or 25 words (descriptive).
What this rule does not cover
- A colon that does not introduce a vertical list (for example, in a ratio, a time notation, or a title/subtitle separator) is not governed by this rule.
How to fix it
Shorten the lead-in text before the colon and/or any oversized list item so each falls within its applicable word-count limit, moving excess detail into the item text or a preceding sentence as needed. If one item needs sub-detail, fold it into a parenthetical at the same list level (per rule 4.3) rather than nesting a sub-list.
Constraints on the fix
- Keep the vertical list structure and the colon; do not flatten the list into a run-on sentence to sidestep the limit.
- Keep all items at a single list level, consistent with rule 4.3 — do not introduce a nested sub-list as a workaround.
Examples
Not STE: To extinguish a possible fire, portable fire extinguishers are installed in these different areas of the aircraft that are described in more detail in the maintenance manual and its supplements:
STE: To extinguish a possible fire, portable fire extinguishers are installed in these areas: - The cockpit - The cabin - The cabin sub-compartment - The crew rest compartment.
Related rules
Where this fits in AI governance
A rule a checker can test is a rule a model can be held to. The same discipline, on the governance side of this site.
- Testing AI systems
Word counting is specified precisely so that a length limit is a test rather than an opinion. - AI system monitoring and logging
Counted deviations per document, over time, are the monitoring metric this section makes possible. - Output validation guardrails
A controlled language is a checkable output constraint. This is the control that treats model output as something to be checked rather than trusted.
Source
ASD-STE100 Issue 9, Section 8 - Punctuation and word count, page 1-8-4.
This page is commentary and does not reproduce the standard. About this rule pack.