# Places and Transitions

> The requirement that a modeled system be expressed as places holding tokens and transitions that move them.

Record: `lex:places-and-transitions`
Kind: constraint
Layer: [Atomic Boundary](https://banes-lab.com/records/layer/atomic-boundary.md)
Canonical: https://banes-lab.com/ontology/lexicon#lex-places-and-transitions

## category

- [Transactions / State / Concurrency](https://banes-lab.com/records/lex-category/transactions-state-concurrency.md)

## referenced-by

- [Petri Nets](https://banes-lab.com/records/arch/petri-nets.md)