# Why can the books lag the chain tip?

BTI's three stages each keep a cursor, and the books can only be written as far as the stages beneath them.

URL: https://blockspace.wiki/answers/why-can-the-books-lag-the-chain-tip/

[BTI](https://blockspace.wiki/glossary/bti/) works in three stages, each with its own [cursor](https://blockspace.wiki/glossary/cursor/): the census counts bytes, the claims stage searches every protocol, and [the books](https://blockspace.wiki/glossary/the-books/) are written last. The books can never pass the claims or the census, so they trail the tip while a stage catches up. They stood at block 972,499, the tip at 972,511 (as of block 972,509, 2026-10-21 17:11:31 UTC).

Sources:

- block.space docs: rankings · https://block.space/docs/rankings
- block.space frontier API (the three tier cursors and the chain tip) · https://block.space/api/frontier
- block.space Sync page: the three tiers, their heights and the latest consensus-hash window · https://block.space/sync
- Blockspace Co. records

Live figures: frontier as of block 972,509, 2026-10-21 17:11:31 UTC

Updated: 2026-10-21