This directory contains a set of constants presets used for testing, testnets, and mainnet.
A preset file contains all the constants known for its target. Later-fork constants can be ignored, e.g. ignore Phase 1 constants as a client that only supports Phase 0 currently.
Configs are not replaced, but extended with forks. This is to support syncing from one state to the other over a fork boundary, without hot-swapping a config. Instead, for forks that introduce changes in a constant, the constant name is prefixed with a short abbreviation of the fork.
Over time, the need to sync an older state may be deprecated. In this case, the prefix on the new constant may be removed, and the old constant will keep a special name before completely being removed.
A previous iteration of forking made use of “timelines”, but this collides with the definitions used in the spec (constants for special forking slots, etc.), and was not integrated sufficiently in any of the spec tools or implementations.
Instead, the config essentially doubles as fork definition now, e.g. changing the value for PHASE_1_FORK_SLOT changes the fork.
Another reason to prefer forking through constants is the ability to program a forking moment based on context, instead of being limited to a static slot number.
Each preset is a key-value mapping.
Key: an UPPER_SNAKE_CASE (a.k.a. “macro case”) formatted string, name of the constant.
Value can be either:
0xPresets may contain comments to describe the values.
See mainnet_phase0.yaml for a complete example.
SSZ SimpleSerialize