# Allocation domains > Nested constraint domains, transmission-owner authority, voluntary membership by spec compliance, and commercial terms that stay outside the protocol. - Repository: g2tf-org/g2tf-standards - GitHub: https://github.com/g2tf-org/g2tf-standards - Human docs: https://grok-wiki.com/public/docs/g2tf-org-g2tf-standards-436ba3f3e0ff - Complete Markdown: https://grok-wiki.com/public/docs/g2tf-org-g2tf-standards-436ba3f3e0ff/llms-full.txt ## Source Files - `architecture/allocation-domains.md` - `architecture/federation.md` - `architecture/overview.md` - `members/allocator.md` - `rfcs/grid-2-rfc-1.pdf` --- --- title: "Allocation domains" description: "Nested constraint domains, transmission-owner authority, voluntary membership by spec compliance, and commercial terms that stay outside the protocol." --- A **Grid 2 Allocation Domain** is the set of Member Elements cleared by a common Allocator (or Allocator hierarchy) against a common set of Grid 1 constraints. The living definition is `architecture/allocation-domains.md` (`Status: Draft — seeking input`), sourced from RFC #1 §Grid 2.0 Membership and Basis of Authority. RFC 2119 / RFC 8174 keywords in that file and in `specs/` / `members/` are normative. No Grid 2 element derives authority from the protocol. G2P, GCAP, and DESP carry and enforce constraints whose authority comes from Grid 1 custodians. ## Definition | Field | Value | |---|---| | Cleared set | Member Elements (Use, Buffer, Source) plus the domain Allocator(s) | | Common bound | One provisioned Grid 1 constraint set | | Nesting | Local transmission congestion zone → utility / balancing authority → regional RTO/ISO | | Smallest domain | One host utility and one flexible load customer | | On-ramp | Transmission-owner "connect and manage"; no capital deployment and no multi-stakeholder consensus required | | Status | Draft — seeking input (living file). RFC #1 is immutable; errata go to Issues labeled `errata` | Every Member Element and Allocator MUST hold a stable element identifier bound to a physical point of interconnection inside a **provisioned** Allocation Domain (`specs/g2p/spec.md` §2). Identifier format is open; the recommended direction is a domain-scoped hierarchical ID that mirrors constraint-domain nesting. ## Nested constraint domains Allocator associated scope is any level of the hierarchy: transmission line → utility load zone → RTO region (`members/allocator.md`). Domains do not command one another. Federation is announce-and-listen; each Allocator clears only against constraints provisioned by its own Grid 1 custodians. ```mermaid flowchart TB subgraph Regional["Regional Constraint Domain"] RA["Allocator(s)"] SM["Source Member"] RBM["Buffer Member"] subgraph UtilA["Utility A Constraint Domain"] UA["Allocator(s)"] subgraph LocalA["Local Constraint Domain"] LA["Allocator(s)"] U1["Use Member A1"] U2["Use Member A2"] B1["Buffer Member A1"] end end subgraph UtilB["Utility B Constraint Domain"] UB["Allocator(s)"] subgraph LocalB["Local Constraint Domain"] LB["Allocator(s)"] U3["Use Member B1"] B2["Buffer Member B1"] end end end TO["Utility transmission owner"] -->|"MUST provision local and regional constraints"| UA TO -->|"MUST provision local and regional constraints"| UB RSO["Regional system operator"] -.->|"MAY add capacity constraints"| RA ``` This is the RFC #1 Figure 6 / `architecture/federation.md` tree. Regional Source and Buffer Members can sit on the regional domain; local Use and Buffer Members sit on the innermost domain that covers their point of interconnection. ### Two interaction patterns | Pattern | Direction | What happens | |---|---|---| | Member ↔ Allocator | In-domain | Members advertise Service Descriptors; the Allocator clears; Members perform verified self-dispatch | | Allocator ↔ Allocator | Coupled zones | Peer Allocators exchange G2P Federation Announcements; each still clears from its own Grid 1 inputs | Treatment of a Member present in overlapping domains (local + regional) is an open item in `architecture/allocation-domains.md`. Do not assume a specified multi-domain commit rule. ## Basis of authority Authority is **anchored in the utility transmission owner**. | Actor | Normative role | |---|---| | Utility transmission owner | MUST provision the Allocator with the local and regional constraints that bound clearing for Member Elements in its domain | | Regional system operator | MAY additionally provision capacity constraints to a regional Allocator | | Protocol stack | Carries and enforces those constraints; does not originate them | | Allocator | Holds no internal intelligence or discretion; deterministic GCAP only | RFC #1 Figure 5 is the single-domain picture: the transmission owner feeds **transmission constraints**, the regional system operator feeds **capacity constraints**, and Allocator(s) clear every minute under GCAP. Hosting and operational responsibility (utility-operated vs. third-party under utility authority) is an Allocator open item. Redundancy (active/standby Allocators per domain) is also unspecified. ## Constraint inputs the domain must provision Each interval, GCAP clears against three input classes (`specs/gcap/spec.md` §2): Zone power production capacity, transmission constraints, and target reserves. Optional: power distribution factors and dynamics from Dynamic Line Ratings. Which existing transmission-owner signals to standardize is a headline Engineering discussion item. In-zone signed requests/offers for the forward time vector. Positions are energy-in-the-interval (v26.0). Across coupled zones. MAY add boundary headroom. MUST NOT relax local constraints. Missing required announcements: clear conservatively as if the boundary contributes no additional headroom. A Commitment MUST identify the interval, the **domain**, and the clearing-inputs version it was computed against. Allocators SHOULD publish (within the domain) the input digest. Publication of that digest is still listed as an Allocator open item. An Allocator MUST NOT clear on stale constraint inputs. On staleness or partition it MUST withhold clearing; Members fall back to Grid 1 baseline. ## Membership Grid 2 has **no admission process** and **no perimeter** (`architecture/overview.md`, Membership without a perimeter). A Member is any asset running a conformant protocol implementation at a point of interconnection covered by a provisioned domain, under commercial terms with its host utility. | Layer | What defines it | What does not | |---|---|---| | Technical membership | Spec compliance at a qualifying POI whose transmission-owner constraints are provisioned to an Allocator | Registration, a central operator, or a universal rollout | | Commercial participation | Domain-level agreements with the host utility | G2P / GCAP / DESP message semantics | | Voluntariness | Distinct from other grid and market requirements; same class of arrangement as emerging connect-and-manage schemes | A requirement that Grid 2 be universally applied | The design assumes willingness of parties to agree on connect-and-manage principles. Grid 2 does not need to be universally applied; it sits inside the Grid 1 context at any scale. Certification / conformance test criteria for "spec compliance" are **not specified**. Wire format, state machines, version negotiation, and conformance test vectors remain "to be specified" in G2P. ### Member kinds in a domain | Kind | Physical asset | Broadcasts | Listens for | |---|---|---|---| | Use | Flexible large load | Per-class request to consume (+) | Per-class commit-% | | Buffer | Storage | Signed charge (+) / discharge (−) offer | Committed dispatch (cleared before any load curtailment) | | Source | Clean-energy supply | Offer to supply (−) over a forward vector | Committed take | | Allocator | Domain constraint set | Per-class commit-% to Members; Federation Announcements to peers | In-zone descriptors; peer announcements | The Allocator never sees internal facility workloads. A Use Member maps workloads to classes at the edge; GCAP clears class-level positions only. ## Commercial terms stay outside the protocol Commercial participation terms are **domain-level agreements**, not protocol fields. `architecture/allocation-domains.md` and DESP §4 both point at Discussion: Commercial terms. A domain MAY constrain the mix of classes a Member can declare (example: a minimum Class C share for expedited interconnection). Those limits live in the domain agreement. Class ordering C → B → A remains mandatory in GCAP regardless of commercial policy. Settlements stay on Grid 1's slower clock. Grid 2 coordinates operation, not prices. RFC #1 Open Questions that stay off the wire: | Topic | Open question (RFC #1) | |---|---| | Enforcement | What commercial terms look like, especially enforcement of flexible capabilities | | Class policy | Whether the standard should give guidance or limits on differential service classes | | Congestion investment | How participating organizations solve direct congestion needs; who decides a new battery | | Rates | How broader rate structures are impacted; how Grid 2-enabled use is charged | | Planning | How Grid 2 connections enter IRP / RTO interconnection processes | GitHub Discussions category **Commercial terms** is the comment channel for those items (`CONTRIBUTING.md`). Do not encode prices, SLAs, or class-mix mandates into G2P messages. Whether domains publish a machine-readable **domain descriptor** (constraint scope, class policy, ramp limits) is an open item. Until that exists, implementers treat class-policy and ramp limits as configuration agreed with the host utility, not as a specified object. ## What the Allocator does inside a domain GCAP is deterministic: identical inputs MUST produce identical allocations. Clearing order: 1. **Headroom** — surplus network capability for the interval 2. **Buffers** — committed dispatch before any load is curtailed 3. **Tiered ramp-down** — DESP order C → B → A, proportional within class; never touching traditional Firm (Grid 1) Outputs apply to the coming interval only and expire with it. Per-class commit-% / committed dispatch / committed take are the only Allocator-to-Member control surface. The total participating pool MUST be sized so simultaneous fallback of all Members stays within manageable Grid 1 aggregate ramp limits. That pool bound is the binding constraint on domain growth; sizing methodology is open. ## Failsafe inside a domain | Condition | Allocator | Members | |---|---|---| | Stale constraint inputs | MUST NOT clear | Missed/stale Commitment → fallback | | Partition of this domain | MUST NOT clear | Element-specific Grid 1 baseline | | Partition of a peer Allocator | Local clearing continues | MUST NOT trigger fallback in unaffected domains | Fallback MUST be locally determinable from the Member's own state and last-known configuration. It MUST NOT depend on reaching a remote peer. Ramp rates agreed with the host utility apply on every transition. ## Open items that change implementers | Item | Owner file | Effect if you implement now | |---|---|---| | Conformance / certification criteria | `architecture/allocation-domains.md` | Spec compliance is declared, not certified | | Machine-readable domain descriptor | `architecture/allocation-domains.md` | Class policy and ramp limits stay in the utility agreement | | Overlapping local + regional membership | `architecture/allocation-domains.md` | Do not invent a dual-commit rule | | Hierarchical element IDs | `specs/g2p/spec.md` §2 | Bind a stable ID to POI + provisioned domain; format is open | | Federation announcement schema | `architecture/federation.md`, G2P §3.3 | Identify announcing domain, interval, coupled-boundary quantities; fields TBD | | Transmission-owner input standardization | `members/allocator.md`, RFC #1 Engineering | Provision the required constraint set; signal catalog is open | | Allocator hosting / redundancy | `members/allocator.md` | Authority stays with the transmission owner either way | ## Related pages Host utility plus one flexible load, transmission-owner constraint provisioning, and the connect-and-manage on-ramp. Announce-and-listen across nested local-to-regional domains; missing announcements do not trip unrelated members. No-discretion deterministic clearing, constraint-authority inputs, withhold-on-stale, and whole-pool ramp sizing. Required Grid 1 constraint set, optional DLR and distribution factors, and the no-relax rule for peer announcements. Membership without a perimeter, NERC/FERC/TSO non-interference, and coordination without prices. DESP A/B/C above Firm, mandatory C-B-A curtailment, and domain class-policy limits that stay in the agreement.