> ## Documentation Index
> Fetch the complete documentation index at: https://invoca-5bd45748-mintlify-17ed87db.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
# Capitalization and punctuation
> Which UI text is title case and which is sentence case, and Invoca's grammar exceptions to AP style.
**This page has no official source and is authored, not transcribed.** Unlike
[Numbers](/invoca-design-system/content/numbers), [Dates and times](/invoca-design-system/content/dates-and-times), [Voice and
tone](/invoca-design-system/content/voice-and-tone), and [Error messages](/invoca-design-system/content/error-messages), no
zeroheight page exists for capitalization specifically. What follows is built from: the one
confirmed grammar rule below, the casing evidence already found while auditing components
against Figma and zeroheight this pass, common practice across other design systems, and
this documentation's own existing pages. Treat every constraint here as **Proposed** and
more provisional than usual until reviewed.
## The base style
Invoca's writing follows **AP Stylebook** conventions, with one confirmed exception: **Invoca
uses the Oxford comma**, where AP style omits it. This is the one rule on this page transcribed
from a direct statement rather than inferred — everything else follows from applying it and
from resolving what AP style itself leaves unspecified for interface text.
| Rule | ✅ Do | ❌ Don't |
| ------------------------------------------------------------ | ----------------------- | ---------------------- |
| Use a comma before the final item in a list of three or more | Calls, texts, and chats | Calls, texts and chats |
## Casing by content type
**The central finding of this page.** Casing is not one rule — it is a per-content-type
decision, and this documentation previously got one of them wrong. This table is the
correction and the reference going forward.
| Content type | Case | Confirmed by |
| ----------------------------------------------------------------------------------- | --------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------ |
| **Button labels** | Title case | zeroheight's Button page, directly — see [TITAN-CASE-01](#constraints) and [TITAN-BTN-13](/invoca-design-system/components/actions/button#constraints) |
| **Error messages, helper text, and other full-sentence messaging** | Sentence case | zeroheight's Error Messaging page, directly — "Use sentence-case for all messaging" |
| **Field labels** | Sentence case | **Proposed** — not directly sourced; assumed consistent with the sentence-case default below until confirmed otherwise |
| **Empty-state title and body** | Sentence case | **Proposed** — carried from the earlier EmptyState page, not stated in the Empty States zeroheight page itself |
| **Page titles, headings, table column headers, menu and option labels, tab labels** | **Unconfirmed** | See [Gaps](#gaps-in-the-current-rules) |
## Two casing systems, and where each one applies
**Title case** (headline style): capitalize the principal words. Lowercase articles (`a`,
`an`, `the`), coordinating conjunctions (`and`, `or`, `but`), and short prepositions (`in`,
`on`, `to`, `of`, `for`) — unless one of them is the first or last word.
| Rule | ✅ Do | ❌ Don't |
| --------------------------------------------- | --------------------- | --------------------- |
| Lowercase short function words mid-phrase | Save Changes to Draft | Save Changes To Draft |
| Capitalize the first and last word regardless | Turn Notifications On | turn Notifications on |
**Sentence case**: capitalize only the first word and proper nouns. This is the default for
anything meant to be read as a sentence rather than scanned as a label — error messages,
helper text, empty-state copy, body text generally.
## Terminal punctuation
| Rule | ✅ Do | ❌ Don't |
| ----------------------------------------------------------- | ---------------------------- | --------------------------- |
| Labels and short action text carry no terminal punctuation | Save changes | Save changes. |
| Full-sentence messages do carry normal sentence punctuation | Enter a valid email address. | Enter a valid email address |
This already matches [Button's Content rule](/invoca-design-system/components/actions/button#content) for "no
terminal punctuation" and the "verb-first" logic behind it — a label is a name for an
action, not a sentence describing one, and names don't end in periods.
## Glossaries
Cited here rather than duplicated — three exist, at different scopes, and none of them is
this documentation's authority on UI terminology specifically:
| Glossary | Scope |
| ---------------------------------------------------- | ----------------------------------------------- |
| The Big Invoca Glossary and Synonyms (Google Sheets) | Broadest — anything related to work at Invoca |
| Invoca Development Glossary (Confluence) | Platform and development-process terms |
| Customer-facing Glossary (docs repo, GitHub) | Terms used across Invoca's public documentation |
**None of these is scoped to product UI copy specifically.** Where a term's everyday name
differs from its technical one — the running example in this documentation is *table* vs.
`DataGrid`, see [TITAN-DIV-10](/invoca-design-system/foundations/divergences#titan-div-10) — the reader-facing
word is this documentation's own call, not something to look up in any of these three.
## Constraints
| ID | Constraint | Rationale |
| ----------------- | -------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------- |
| **TITAN-CASE-01** | Button labels are title case: capitalize principal words, lowercase short function words unless first or last. | Directly stated in zeroheight's Button page. |
| **TITAN-CASE-02** | Error messages and other full-sentence UI copy are sentence case. | Directly stated in zeroheight's Error Messaging page. |
| **TITAN-CASE-03** | The Oxford comma is used in any list of three or more items. | Directly stated in source. |
| **TITAN-CASE-04** | Labels and short action text carry no terminal punctuation. Full-sentence messages do. | A label names an action; a message describes a situation. Names don't take periods. |
| **TITAN-CASE-05** | Field labels are sentence case. **Proposed**, pending confirmation — see [Gaps](#gaps-in-the-current-rules). | Assumed consistent with the sentence-case default until a source states otherwise for this specific content type. |
## Gaps in the current rules
Divergences, open decisions, and undocumented gaps for Capitalization and punctuation.
## Why it works this way
**Title case for buttons, sentence case for messages, tracks a real distinction rather than
being an arbitrary split.** A button label names an action — closer to a headline or a proper
noun than to a sentence — and headline style is what most editorial conventions use for
exactly that kind of short, scannable text. An error message or a line of helper text is meant
to be read fluently, the way a sentence is read, and sentence case is what makes prose read as
prose rather than as a row of scattered emphases. The split isn't Invoca-specific; it shows up
across most design systems that distinguish action labels from body copy, which is part of why
it survived unnoticed as "sentence case" here for as long as it did — it looks plausible
because the *pattern* is common, even where this documentation had the *assignment* backwards.