PCB1 — Parameter Block Encoding (FCS/1)

Status: Approved Owner: Architecture Version: 1.0.0 SoT: Yes Last Updated: 2026-02-21 Linked Phase Pack: PH07 Tags: [execution, parameters, deterministic]

Document ID: PCB1 Layer: L2 — Parameter block encoding for FCS/1 descriptors

Depends on (normative):

DDS — PCB1 envelope and TLV layout (DDS §7.3)
ASL/1-CORE v0.4.x — logical value model

0. Purpose & Scope

PCB1 defines a deterministic, canonical encoding for parameter blocks used by FCS/1 descriptors. It standardizes slot manifests, slot data ordering, and arity validation.

1. Logical Model

A PCB1 parameter block is a two-part payload:

PCB1 {
  slot_manifest : list<Slot>
  slot_data     : bytes
}

Slot {
  index  : uint32
  name   : string
  type   : enum
  digest : bytes[32]
}

Slots MUST appear in ascending index order. The slot_data is a packed byte sequence that respects the manifest ordering.

2. Canonical Encoding

The canonical byte encoding is defined by DDS §7.3:

COR/1 envelope with MAGIC="PCB1", VERSION=0x01, FLAGS=0x00.
Strict TLV order; no padding.
Required TLVs:
- slot_manifest (0x50) — BCF/1 list of slot descriptors.
- slot_data (0x51) — packed bytes aligned with the manifest.

3. Validation Rules

Implementations MUST reject PCB1 payloads that violate any of the following:

TLVs are not in strict ascending order, or appear more than once.
slot_manifest entries are not sorted by index.
Slot digest mismatches (ERR_PCB_DIGEST_MISMATCH).
Non-deterministic or duplicated manifest ordering (ERR_PCB_MANIFEST_ORDER).
Arity mismatch between PCB1 slot count and the enclosing FCS/1 descriptor (ERR_PCB_ARITY_MISMATCH).

4. Conformance

An implementation is PCB1–conformant if it:

Emits the exact canonical encoding in DDS §7.3.
Enforces the validation rules in §3.

1.9 KiB Raw Blame History Unescape Escape