Requirement
Set all UI copy in sentence case — capitalise the first word and any proper or branded noun, and lowercase everything else. This holds everywhere text appears: headings, page titles, buttons, labels, menu items, tab names, and running prose. Do not use Title Case ("Submit Your Report", "View Project Details") and do not capitalise a mid-sentence word for emphasis.
Sentence case is easier to read and scan, sounds more human than the shouty register of Title Case, and reserves capitals for the words that genuinely carry them — the names of people, products, programmes, and places. When only proper nouns are capitalised, the capital itself becomes a signal.
This applies to user-facing copy. Genuine acronyms (PDF, API) and product, programme, and feature names keep their established capitalisation.
See also: TYP-4 bans all-caps text (a styling transform, or a shouted string); CNT-12 is
the neighbouring rule for the other capitalisation failure — Title Case, which passes
TYP-4 because it uses no uppercase transform yet still breaks sentence case. TYP-4 catches
SUBMIT; CNT-12 catches Submit Your Report. This control also makes the
grammar-mechanics.mdx "sentence case everywhere" rule enforceable.
Rationale
Title Case reads as a heading style borrowed from print mastheads; on a daily work tool it adds visual noise and a faint corporate tone without adding meaning. Sentence case matches how people actually write, keeps buttons and labels calm, and — because capitals are rationed — lets a proper noun stand out where it should. The rule is a strong default with narrow, well-defined exceptions (proper nouns, branded names, genuine acronyms), so it is L2: deviate only with a recorded reason, not silently.
Passes when
- A heading reads "Submit your report", not "Submit Your Report".
- A button reads "View project details", not "View Project Details".
- A proper or branded noun keeps its capital mid-sentence: "Open in Planboard", "Sync to Ledgerly".
- A genuine acronym stays capitalised: "Upload the PDF record".
Fails when
- Title Case in a heading, label, button, tab, or menu item: "Submit Your Report", "View Project Details", "Manage All Members".
- A common (non-proper) mid-sentence word capitalised for emphasis: "Please Confirm before you continue", "This is a Draft".
- A page or section title that capitalises every significant word rather than just the first word and any proper noun.
How to verify
Hybrid. Deterministic half — a planned checks/content-lint.py heuristic flags
headings, labels, and button strings where multiple words begin with a capital (a
Title-Case signal), leaving proper-noun exemption to review. Until the heuristic ships,
verify manually against the rendered copy and label it "verified manually". Judgment half —
the evaluator reads each heading, label, button, and sentence and confirms only the first
word and genuine proper or branded nouns are capitalised.
Evaluator guidance
Quote the offending string in every finding and give the sentence-case rewrite.
Flag:
- Title Case on any heading, label, button, tab, or menu item where the extra capitals are not proper nouns: "Submit Your Report" → "Submit your report".
- A common mid-sentence word capitalised for emphasis: "This is a Draft" → "This is a draft".
Do not flag:
- Proper nouns — names of people, organisations, places, public bodies.
- Product, programme, and feature names with established capitalisation: the product's own name, or a feature name where it is the branded term.
- Genuine acronyms (PDF, API, URL) — already exempt under TYP-4.
- The first word of a heading or sentence, which is always capitalised.
Waiver
rationale (L2) — inline dx-waive CNT-12 reason="..." at the deviation site. A
policy-mandated title or programme name that must appear verbatim in Title Case is the
canonical waiver case.