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Block

An ALX Block is a verifiable data object containing application-defined content, deterministic identities, and declared parent relationships. ALX canonicalizes and hashes content without interpreting it.

Block Model​

Every Block contains exactly five required protocol fields.

type Block = {
  blockHash: string;
  contentHash: string;
  parentHashes: string[];
  content: unknown;
  protocolVersion: "1";
};
FieldDescription
contentApplication-defined ALX value. Canonicalization lists the supported values.
parentHashesblockHash values of the direct parent Blocks, normalized: lowercase, deduplicated, and sorted. An empty array marks a root Block.
contentHashHash of the canonicalized content.
blockHashHash of the canonicalized content together with the normalized parentHashes.
protocolVersion"1" in protocol version 1. Excluded from both hash calculations.

Block Identity​

ALX derives both hashes with domain-separated Keccak-256. Identical content produces the same contentHash under any parent set, and a different normalized parent set produces a different blockHash. Parent order and duplicate parent entries change neither hash. See Block Identity for derivation and hash format.

Block Validation​

validateBlock(block) rejects a malformed record with an error: missing or extra fields, a protocolVersion other than "1", or a malformed hash. For a well-formed record, validateBlock() returns ok: true only when:

  • the recomputed contentHash and blockHash equal the recorded values;
  • the recorded parentHashes are already normalized; and
  • parentHashes does not contain the Block's own blockHash.

Block validation does not establish parent availability or Graph validity. Validate Blocks lists the error identifiers, and Lineage Graphs covers Graph verification.

Parent Relationships​

Each entry in parentHashes declares a dependency on a direct parent Block, and connected Blocks form a derivation Graph. See Parent Relationships for normalization rules and constraints.

When to Create a Block​

Create a Block when application-defined content requires deterministic identity, declared dependencies, independent validation, or composition with other Blocks.