Tapestry
What does a tech card's prerequisite mean, such as a tier on another track or a symbol like Telephone or a worker?
The rulebook gives the top-row prerequisite rule and an example with a track tier.
- Tapestry rulebook · Rulebook · Technology — Invent
It is a requirement that you, or one of your two neighbours, meet at the moment you upgrade the card to the top row. A track prerequisite means being in or past that tier right then. Upgrading to the middle row has no requirement.