How the Great Britain energy system is layered in May 2026, from physical assets to the Common Information Model

Where the Great Britain energy system architecture stands in May 2026

The architecture has settled at the top and is still moving through every layer below. NESO has been running for nineteen months as a public corporation under the Energy Act 2023, with a remit covering electricity balancing, transmission planning, gas system coordination and (in time) hydrogen and CCUS planning. The transmission owner separation that the 2023 Act enforced is now operational in practice: National Grid Electricity Transmission keeps the physical assets in England and Wales under Ofgem's RIIO-T price control, NESO sits in a separate corporate vehicle accountable to the Secretary of State, and the connection-offer, ancillary-procurement and reinforcement-prioritisation decisions are now made with different incentives from the ones that applied between 1990 and 2024. That single governance change shapes how every other layer reads.

The Centralised Strategic Network Plan methodology was approved by Ofgem in April 2026.³⁴ The transitional T-CSNP that bridges from the Network Options Assessment is due in June 2026, and the first full CSNP delivery is due by the end of 2028. NESO published Connections Reform Gate 2 detailed results in April 2026, with 283 gigawatts of generation and storage and 99 gigawatts of demand progressed across two delivery phases.³⁸ The Strategic Spatial Energy Plan methodology was published in May 2025 with the first iteration due in Q4 2026, a public consultation in early 2027, and the final SSEP in Autumn 2027.²¹ The Review of Electricity Market Arrangements settled in summer 2025 in favour of Reformed National Pricing with the SSEP as the centrepiece of strategic planning.³⁵ So the strategic-planning architecture, the strategic network architecture and the connections architecture are all settled at the methodology level, with the operational outputs still landing in 2026 to 2028.

The data layer is moving in parallel. The Long Term Development Statement publishes its Stage 2 on 29 May 2026 under the third derogation letter of 13 May 2026, which reshaped Stage 2 contents while holding the publication date.² The duty itself sits in SLC 25.2 of the Electricity Distribution Licence, with the technical artefacts curated through the BSI Engagement Hub.^{1 4 23} Stage 2 carries the validated CIM model for around eighty percent of the distribution network at 11 kilovolts and above, with the Stage 3 production deferred under the same letter to 30 November 2026. The Energy Digitalisation Framework was published on 23 March 2026 by DESNZ and Ofgem, formally adopting the layered digital-stack vision the Energy Digitalisation Taskforce had recommended in 2022 and committing NESO to deliver a first-draft architectural reference framework by August 2026.¹² The Distribution Code Issue 59 was published on 24 April 2026 and the Grid Code Issue 6 Revision 37 was published on 13 April 2026; the rule book the architecture rests on moved twice in six weeks.^{6 7}

Market-wide Half Hourly Settlement passed Milestones M10 to M13 in early 2026 with ten million Meter Point Administration Number initiations completed; the programme cuts over in July 2027 under BSC modification P408.^{20 26} The Capacity Market T-4 for 2029 to 2030 cleared at twenty seven pounds ten per kilowatt year for 40.1 gigawatts in February 2026 and the T-1 for 2026 to 2027 cleared at five pounds per kilowatt year for 7.2 gigawatts in March 2026.¹⁴ Contracts for Difference Allocation Round 7 reported on 14 January 2026 with a record 8.4 gigawatts of offshore wind awarded.³⁶ Ofgem became the heat networks regulator on 27 January 2026 under the Heat Networks (Market Framework) Amendment Regulations.³⁷ The Data (Use and Access) Act 2025 brought its first commencement orders into force in February 2026, including Section 138 and the majority of Part 5's data-protection provisions.^{19 39 40} The Wylfa site contract for three Rolls-Royce small modular reactors was signed in April 2026.⁴¹

So in May 2026 the architecture has a settled high-level shape and a live set of operational reforms running through every layer below. The questions are no longer about whether NESO is the operating-control body, whether the data model is CIM, whether the market is nationally priced or zonally priced, or whether a Centralised Strategic Network Plan is the instrument that bridges system planning and network planning. They are about how the layered model holds together as each operational reform lands, which layer absorbs the slack when a delivery date slips, and what new coordination problems show up at the seams between layers. The six-layer model below is the working frame for those questions.

The six-layer view of the Great Britain energy system in May 2026, layer by layer

The six layers are not equal. The customer layer is where every reform is judged. The data layer is where every reform is observable. The market layer is where capital and behaviour respond. The operating-control layer is where dispatch happens in seconds and minutes. The physical-asset layer is where the steel, copper and concrete are. Governance is the spine that authorises, constrains and routes decisions across the other five. Each is set out below with the institutions, the regulatory hooks and the operational artefacts that anchor it in May 2026.

The Great Britain energy operating model in May 2026: decision rights, escalation, delivery interactions

Naming the actors is the easy step. The harder step is mapping who decides what on an ordinary working day. Most of the confusion in policy debate comes from asking the wrong actor for a decision they do not have authority to take. The operating model below sets out the decision rights, the escalation chain, and the delivery interactions that bind the six actor families together. Read together with the governance-spine section above, it is the practical answer to the question "where in the system does this decision actually get made".

Decision rights, sorted by what the decision changes

Each decision type belongs to a specific actor. Crossed wires arise when a decision is requested from an actor outside its remit.

• Real-time dispatch belongs to NESO (electricity) and National Gas (gas). Both operate within rules set by Ofgem and Directions from DESNZ in emergencies. The Electricity Supply Emergency Code, invoked only in the most severe operating conditions, is the legal instrument for state-level direction of dispatch.
• Connection offers belong to NESO for transmission and the DNOs for distribution. Both operate under CUSC (transmission) and DCUSA (distribution). Connections Reform Gate 2 results were issued by NESO in April 2026.³⁸
• Price control determinations belong to Ofgem. NESO, the transmission owners, the DNOs and the GDNs all operate under periodic price controls; the live cycle in May 2026 is RIIO-ED2 (distribution, 2023-28), RIIO-T2 (transmission, 2021-26 with RIIO-T3 in setting), RIIO-3 (gas distribution), and RIIO-ESO (NESO's own control).
• Code modification approval belongs to Ofgem in its statutory role under the Electricity Act 1989. Code panels (the Grid Code Review Panel, the Distribution Code Review Panel, the BSC Panel, the CUSC Panel, the DCUSA Panel, the STC Panel, the UNC Panel, the SEC Panel, the REC Panel) recommend; Ofgem decides.
• Licence variation belongs to Ofgem under the Electricity Act 1989 and Gas Act 1986. Most variations follow a public consultation; significant variations follow a formal modification process with statutory time limits.
• Settlement belongs to Elexon for electricity and Xoserve for gas. Both administer the relevant industry code and resolve disputes between trading parties under the code rules.
• Consumer dispute resolution belongs first to the supplier, then to the Energy Ombudsman after eight weeks of unresolved engagement, with decisions binding to ten thousand pounds. Citizens Advice supports consumers through the process but does not adjudicate.
• Strategic policy belongs to DESNZ via Strategy and Policy Statements that set Ofgem's strategic context, and via primary legislation when the framework itself needs to change. Only primary legislation can override that framework.

The escalation chain for a typical incident

A small example clarifies the chain. A household customer is wrongly billed twice for the same consumption period. The customer raises the issue with the supplier. The supplier reviews and responds; if the supplier accepts the error the case closes there. If the supplier rejects the customer's view and eight weeks pass without resolution, the customer can escalate to the Energy Ombudsman, whose decision is binding on the supplier up to ten thousand pounds. Citizens Advice can support the customer through both stages. Ofgem does not adjudicate the individual case; if the same pattern of erroneous billing affects many customers, Ofgem can investigate the supplier's processes systemically and ultimately take enforcement action under the standard licence conditions of the supply licence. The case the supplier and the Ombudsman handle is the individual; the systemic risk Ofgem addresses is the population.

Delivery interactions, where the layered model becomes a working relationship

Several of the most important reforms in delivery in May 2026 work because four or five actor families interact in a structured way. A live example is the LTDS programme. Ofgem holds the regulatory hook (SLC 25.2 of the Electricity Distribution Licence; the Direction of 30 April 2024; the three derogation letters of November 2024, March 2025 and 13 May 2026).^{1 2 23} BSI is the technical curator of the artefacts under contract with Ofgem; the Engagement Hub at https://cim.bsigroup.com/ is where the LTDS profile, shapes and sample files are made available to registered users.⁴ The DNOs are the regulated parties; they prepare the validated CIM models against the cadence Ofgem set and the technical artefacts BSI curates. The ENA coordinates the DNO-side technical engagement. NESO is the consumer of the data for whole-system planning; its participation in the GC0139 Grid Code modification on enhanced planning-data exchange formalises that relationship.³ The Distribution Code Review Panel governs Distribution Code modifications that the LTDS reforms sometimes touch.

Another live example is MHHS. Elexon runs the programme under BSC P408.²⁶ The DCC operates the smart-meter wide-area network and the DUIS interface. Suppliers retool their billing systems for half-hourly settlement. The DNOs prepare their settlement-data ingestion pipelines for the half-hourly data the new arrangements release. Ofgem approves the BSC modification and oversees the migration milestones. DESNZ sets the policy direction. The migration cutover in July 2027 is the programme's single largest event; the preceding eighteen months are the year-and-a-half of multi-party readiness work that makes the cutover work.²⁰

A third example is the CSNP. NESO submits the methodology to Ofgem.²² Ofgem approves it (the approval decision arrived in April 2026³⁴). The transmission owners are the asset-investing parties whose portfolios the CSNP shapes; their RIIO-T3 price control will fund the projects the CSNP directs. The DNOs are affected through the transmission-distribution interface, including the demand-headroom and connection-queue impacts. DESNZ uses the CSNP to inform the broader Clean Power 2030 trajectory and the SSEP iterations.

What all three examples share is that no actor finishes a reform on its own. The licensee party that holds the obligation, the regulator that enforces it, the technical curator that owns the artefacts, the operator that consumes the data, the code panel that governs the rule book, and the policy department that sets the strategy all show up. Reading a reform without naming each of those actors and what they are responsible for is the most common cause of policy proposals that get stuck in implementation.

The 1 October 2024 transition that the operating model is still absorbing

From 1990 to 2024, National Grid plc held both the system-operator function for Great Britain electricity and the transmission owner role in England and Wales. The Energy Act 2023 separated them. NESO is now a public corporation accountable to the Secretary of State; National Grid Electricity Transmission is now a regulated transmission owner under RIIO-T price control with no shared corporate parent with the system operator. The legal separation took effect on 1 October 2024. The operational consequences are still being absorbed across the sector: the connection-offer prioritisation logic, the balancing-actions logic, the ancillary-services procurement, the reinforcement-planning logic. Each of these now runs under different incentives from the ones in place for the previous three and a half decades.

That single transition is the largest operating-model change since the 1989 Act. The full absorption is the kind of cross-actor relearning that takes years rather than months: how does NESO talk to a transmission owner it no longer shares a parent with; how does Ofgem regulate them differently; how do DNOs route their planning interactions; how does DESNZ steer through a Strategy and Policy Statement that lands on two separate counterparties instead of one. The bones of the answer are clear from the 2023 Act and the licences. The practice is still maturing.

Digital architecture under the Energy Digitalisation Framework, March 2026 onwards

The digital architecture is the practical detail of the data layer above. The Energy Digitalisation Framework, published jointly by DESNZ and Ofgem on 23 March 2026, is the first formal architecture-vision document for the Great Britain energy system as a whole.¹² Its precursors are the BEIS, Ofgem and Innovate UK Energy Digitalisation Strategy and Action Plan of 20 July 2021, the Energy Digitalisation Taskforce report of January 2022 (which introduced the "digital spine" concept), and the joint government response of 19 July 2022. The Framework consolidates those precursors and adds three commitments: a new digitalisation coordination function, four functional data domains, and an obligation on NESO to deliver a first-draft architectural reference framework by August 2026. The digitalisation coordination function is due for consultation by end-2026.

The five-layer digital stack with Great Britain exemplars

The most useful map of the digital architecture is a five-layer stack from physical assets at the bottom to applications at the top. Each layer carries specific Great Britain platforms.

The Ofgem L1 to L5 activity model

Ofgem's L1 to L5 activity model, set out in its January 2022 CIM regulatory approach paper, is the most useful frame for placing any new Great Britain digital instrument on a single map.^{4 5} It scales from formal standards downwards.

The four functional data domains in the Energy Digitalisation Framework

The Framework defines four functional data domains, each with a domain coordinator working under the digitalisation coordination function.

• Core energy system service domain: covers the transmission and distribution operational data, the system-operator dispatch data, the network-planning data (LTDS, ETYS, SSEP, CSNP), and the wholesale, balancing and ancillary market data.
• Behind-the-meter asset domain: covers the data on assets sitting between the meter and the consumer (rooftop solar, batteries, EV chargers, heat pumps, smart appliances) including their registration, performance and dispatchability for flexibility services.
• Consumer domain: covers the consumer-facing data (tariffs, contracts, redress paths, complaints, switching, vulnerability registration) and the consumer-consent infrastructure for sharing meter and household data with third parties.
• Metering data domain: covers the smart-meter readings, the SMETS1 and SMETS2 device data, the meter-asset register, and the settlement-data path that runs from the meter through MHHS to the supplier and the BSC.

The Framework's seven principles set the test each domain has to meet: trusted and secure (NCSC alignment, identity, encryption, certificates); interoperable by design using common, open and recognised data standards (L1 to L5 alignment, CIM, CGMES, CDPSM); simple, accessible and user friendly (API-first, OpenAPI, AsyncAPI, friendly developer experience); responsive and future proof (versioning, backward compatibility, evolution paths); efficient and cost effective (reuse over rebuild, commodity over bespoke); innovative and competition-driven (open APIs, market access, third-party integration); and deliverable (realistic timelines, known funding, clear governance).

The integration patterns under the Framework

Five integration patterns dominate the current architecture, each suited to a different use case.

The DIP went live in August 2025 and surpassed one billion messages on 16 March 2026, a useful operational indicator of the shift toward event-driven messaging in settlement infrastructure.¹⁶

The semantic-model lineage

IEC 61970-301:2022 carries the CIM base. IEC 61970-600 carries CGMES 3.0 for ENTSO-E exchange. The LTDS profile constrains the CIM for Great Britain long-term planning use, with SHACL shapes carrying the validation rules. IEC 61968-13 carries CDPSM for distribution-side unbalanced network exchange. Each step inherits from the layer above and constrains what the layer below has to deliver.⁵ The Common Information Model section below describes this lineage in more detail, with the class hierarchy a reader needs to open an LTDS file.

The cyber and trust spine

The cyber stack runs the Network and Information Systems Regulations 2018 (which designate Operators of Essential Services, including the electricity system operator, the transmission owners, the DNOs and large gas operators), the NCSC Cyber Assessment Framework, mutual Transport Layer Security and OAuth 2.0 or OpenID Connect for authentication, and the DCC's Smart Metering Key Infrastructure (with the PKI-E programme cutover in March 2026). Ofgem published an updated NIS Guidance for Downstream Gas and Electricity Operators of Essential Services in January 2026, covering distribution licensees, the system operator and gas operators alike.

The data-protection layer under the DUA Act 2025

The Data (Use and Access) Act 2025 received Royal Assent on 19 June 2025; its core provisions came into force on 5 February 2026 through SI 2026/82, with Section 138 in force on 6 February 2026 through SI 2026/31.^{19 39 40} Schedule 16 of the Act covers smart-meter communications.²⁸ The DESNZ Energy Smart Data and Privacy Framework sets the operating expectation for how energy-smart data is shared and protected across the ecosystem.²⁹ Together with UK GDPR (now consolidated post-DUAA) and the NIS Regulations, the legal stack covers identity, consent, encryption, storage limitation, and lawful basis for the data flowing through every part of the digital architecture.

Common misreadings of the Great Britain digital architecture

Several specific misreadings recur in writing about Great Britain energy digitalisation. The Energy Digitalisation Framework was not first published in 2022; the 2022 milestone is the Energy Digitalisation Taskforce report, a separate document. The Framework itself is 23 March 2026.¹² BS EN ISO/IEC 5392 is not the energy semantics standard; that standard (ISO/IEC 5392:2024) is an AI knowledge-engineering reference architecture. The Great Britain-relevant smart-grid reference architecture standard is BS IEC SRD 63200:2021 (the extended SGAM). The Balancing Mechanism Reporting Service retired on 31 May 2024; the Insights Solution and IRIS API replaced it, with the legacy URL still resolving while the data flows through the new endpoints. The Open Balancing Platform progressively succeeds the legacy balancing-dispatch IT across 2024 to 2027; the Balancing and Settlement Code remains as the rule book. The DCC stores no meter data of its own; it is a pipe with two-layer cryptography (DCCKI and SMKI) ensuring end-to-end encryption. The Distribution System Operator is a maturity badge on a DNO licensee, not a separate licensed body. NESO replaced the National Grid Electricity System Operator, a previous subsidiary of National Grid plc; National Grid plc still owns National Grid Electricity Transmission.

The Common Information Model behind LTDS publications and CGMES exchanges, May 2026

The Common Information Model is the semantic layer the whole Great Britain digital architecture rests on for network data. It gives Great Britain network data a shared vocabulary across operators, vendors, regulators and analysts. For a Great Britain analyst, its practical value is interoperability: one shared vocabulary lets the data layer publish models against a single standard rather than against bespoke spreadsheets or vendor-specific exports. The LTDS reform of 2024 onwards is the largest single Great Britain application of CIM in published form; the LTDS-basics page on this workspace is the deep reference for how the model is structured, how mRIDs resolve, how SHACL validates a CIM profile, and where to download the actual artefacts.

The CIM mental model

A CIM file is a graph of identified objects, and a profile constrains which parts of that graph must appear for a particular publication. Read in that order, the model becomes tractable. Every CIM object inherits from IdentifiedObject; every IdentifiedObject carries an mRID (machine-readable identifier, formatted as a UUID), a name and a description. PowerSystemResource specialises IdentifiedObject to model the physical or logical objects on a power system. Equipment and EquipmentContainer both specialise PowerSystemResource: Equipment is the asset (a transformer, a circuit breaker, a line segment); EquipmentContainer is the grouping (a substation, a voltage level, a bay). ConductingEquipment specialises Equipment to model the current-carrying subset. The LTDS profile is the specific constraint set that says which subset of the full CIM is required for a Great Britain LTDS publication, and which classes, attributes, relationships and cardinalities are mandatory for each publication stage.

The CIM standards stack

The LTDS profile families

Raw CIM is broad. A profile narrows the model to a specific exchange and says which classes, attributes, relationships, datatypes and cardinalities are required. The Great Britain LTDS uses several profile families, each with a specific job.

The Stage 2 publication on 29 May 2026 and what the 13 May 2026 derogation reshaped

The third derogation letter is the most recent CIM-relevant instrument. It is signed by Steve McMahon, Director, Network Price Controls at Ofgem.² It does three things relevant to the model. First, it tightens the Stage 2 content scope to what is operationally required for the May 2026 publication, with explicit cardinality and validation rules that previously sat across multiple supplementary documents. The Stage 2 deliverable carries the validated CIM model for around eighty percent of the distribution network at 11 kilovolts and above, sufficient for whole-system planning use by NESO and for the live development of the GC0139 Grid Code modification on enhanced planning-data exchange.³ Second, it holds the publication date at 29 May 2026, so the DNOs absorb the content change without slipping the date. Third, it defers Stage 3 production to 30 November 2026, providing a working window for the SHACL validation of the topology, the connectivity reconciliation across DNO boundaries, and the heatmap publication to land coherently.

Working with CIM files

There are three sensible methods to work with CIM data in May 2026: use a vendor planning tool that loads CIM natively, load the RDF into a graph database or triple store, or parse it directly with an RDF library. Each suits a different job.

The practical rule is simple. If a file fails SHACL validation, fix the shape problem before using it for analysis. If the file passes validation, still check whether the source, version and publication notes are appropriate for the question. A Stage 2 file with around eighty percent network coverage is the right input for many planning questions and the wrong input for some asset-rating questions that need full coverage; the publication note settles which is which.

The deep dive on the LTDS and how it sits inside the Great Britain CIM landscape is at /gb-energy-workspace/ltds-basics. That page covers the SLC 25.2 hook in full, the LTDS profile in detail, the SHACL validation pipeline, the mRID handling across DNO boundaries, the role of the BSI Engagement Hub in artefact curation, and the technical specifics of the May 2026 derogation. The two pages are designed to be read together: the architecture page sets the system view and the layered map; the LTDS-basics page gives the operational detail at the publication level.

How to read a reform proposal through the six layers, May 2026

The architecture is most useful as a diagnostic tool. Given a reform proposal, the six-layer test narrows where to look before it narrows what to do. The rule of thumb runs as follows. First identify which layer the reform primarily acts on. Then identify which layers it depends on. Then ask which actor families have decision rights at each of those layers. Then check the cyber, data-protection and licence-condition implications. Then look for the cross-layer interactions that the proposal cannot avoid.

Worked examples make the rule concrete. The Accelerated Strategic Transmission Investment programme, with twenty-six high-voltage projects approved to 2035, acts primarily on the physical-assets layer. It depends on the governance spine for the funding approval (RIIO-T2 and RIIO-T3 price controls), on the operating-control layer for the planning interactions (CSNP and ETYS), and on the data layer for the network models used in planning. The actor families are Ofgem (price control determination), DESNZ (strategic direction), NESO (planning), the transmission owners (delivery) and the DNOs (transmission-distribution interface).

The Transitional Connections Reform (TM04 and its successors), with the Gate 2 results published in April 2026, acts primarily on the governance and data layers.³⁸ A rule change to CUSC plus a process redesign plus an IT rebuild for the connections-queue management. It depends on the markets layer for the price signals that the queue is filtering, on the operating-control layer for the system-impact studies that gate offers, and on the physical-assets layer for the consequential reinforcement plans. Actor families are NESO (process owner), Ofgem (CUSC approval), the transmission owners and DNOs (study and offer counterparties), and DESNZ (strategic policy).

MHHS acts primarily on the data layer. A new data flow (the Elexon DIP), changed settlement rules (BSC P408), and systems rebuilt across around sixty organisations.^{20 26} It depends on the customer layer (supplier billing and tariff design), on the markets layer (settlement runs), and on the physical-assets layer (the meter population). Actor families are Elexon (programme owner), the suppliers (counterparties), the DCC (smart-meter operator), the DNOs (data ingestion), Ofgem (BSC modification approval), and DESNZ (strategic direction).

The NESO launch of 1 October 2024 acted primarily on the governance layer. Assets and IT transferred largely intact; what changed is institutional ownership, accountability and mandate. It has shaped the other layers over the eighteen months since: how connection offers are timed, how reinforcement is prioritised, how ancillary procurement runs, how the planning instruments (SSEP and CSNP) line up. Each is the operating-model side of a governance change, and each is the kind of cross-layer relearning that takes years.

Dynamic Containment, as a frequency-response product, acts primarily on the data and operating-control layers (a new response product specification, a new procurement IT path, new operational dispatch rules). It depends on the physical-assets layer (the battery storage installed to provide the service), on the markets layer (the procurement run by NESO), and on the governance spine (the code modifications that authorise the product).

The Energy Digitalisation Framework of 23 March 2026 acts primarily on the data layer, with the explicit obligation on NESO to deliver a first-draft architectural reference framework by August 2026.¹² It depends on the governance spine (the Strategy and Policy Statement that follows it), on the customer layer (the consumer-consent and smart-data sharing arrangements), and on the operating-control layer (the integration patterns that the operating systems have to adopt).

The LTDS reform sits across the data and governance layers in roughly equal measure.^{1 2} The data-layer impact is the move from spreadsheets to a validated CIM model published on a regulator-set cadence. The governance-layer impact is the SLC 25.2 mechanism that makes the cadence enforceable and the three derogation letters that have shaped the actual schedule. It depends on the operating-control layer (NESO is the largest consumer of the data for planning), on the physical-assets layer (the LTDS model is a description of the physical network), and on the customer layer at the longer horizon (the headroom information eventually shapes connection offers that customers experience).

What every example shares is that the layer where a reform "lives" is not the only layer it touches. The reforms that get stuck in implementation are usually the ones that ignored a cross-layer dependency. The reforms that land cleanly are usually the ones that named every actor family that had to act, and built the coordination into the programme from the start. The architecture page is therefore most useful as a checklist: which layer, which actors, which dependencies, which cyber and data-protection implications, which cross-layer interactions to engineer rather than discover.

The other use is as a reading aid for the rest of the workspace. Pillar 3 on the workspace home is the network and LTDS pillar; the layers and CIM sections above are the architecture-side complement to that pillar. Pillar 4 is markets; the operating-model and the markets layer above are the architecture-side complement to that pillar. Pillar 5 is energy data; the digital architecture section above is the architecture-side complement to that pillar. Pillar 7 is digital infrastructure, scenarios and tools; the Energy Digitalisation Framework section above is the architecture-side complement to that pillar. The pillars give the routes a reader will take; the architecture page gives the system view that ties them together.