Part

Part divides a plan’s sections into numbered acts. Each marker renders as a borderless, surface-tinted band carrying an accent PART N tag and the act title, and every section after it belongs to that act. Big Plan derives slide numbers, sidebar navigation grouping, and TableOfContents group headers from the dividers, so the deck structure is authored exactly once.

When to use it

Group a plan of roughly five or more sections into about three acts, canonically Context, The proposal, and Shipping & your review. A short plan whose sections already read in one breath does not need dividers.

Authoring

<Part title="Context" />

<Slide type="status-quo" />

## Inline retries delay checkout

...

## Success looks like

...

<Part title="The proposal" />

## The retry queue

...

The contract

• title is required and non-empty; it names the act, never its number.
• Part is self-closing and rejects body content.
• Numbers are assigned in document order at render time; a title containing its own number would read “Part 1: 1. Context”.

Each violation fails validate and render with a positional diagnostic. Run big-plan guidance Part for judgment-level usage guidance.