Terminology¶

Cloud-Native DCS presents itself to end users as a control system. The Kubernetes cluster underneath stays out of user-facing language. This page maps user-facing terms to the underlying infrastructure concepts.

User-Facing Terms¶

User Term	Infrastructure	Notes
Control system	Kubernetes cluster	The overall deployment of Cloud-Native DCS
Controller	Kubernetes node	A physical computing device — an edge device such as an x86_64 industrial PC
Site	Namespace (`site-{name}`)	A physical location; maps to a Kubernetes namespace
Enterprise	Cluster-scoped CRD	Top-level organization
Unit runtime	Pod	Per-unit pod that bridges K8s and hardware
Enroll a device	Register a joined node as a Controller	Joining the node to the cluster is the deployment layer's job (machine config, join token, …); the product then binds the node to a site Controller. See Device Enrollment.
Web UI	Gateway static site at `https://<gateway>/`	Three role-aligned endpoints share one browser session
HMI (Human-Machine Interface)	Gateway endpoint `/hmi`	The operations endpoint specifically — live process display, batch execution, alarms. Not a synonym for the whole Web UI.
System endpoint	Gateway endpoint `/system`	Engineering workspace: configuration, recipes, diagnostics
Data endpoint	Gateway endpoint `/data`	Production information: trends, audit trail, batch records, alarm history

ISA-88 Terms¶

The terms below are defined in ISA-88.00.01 Clause 3 and used throughout the Web UI, CRDs, and this documentation. The right column shows how each term maps to a Cloud-Native DCS resource.

Physical model¶

The "Closest analog" column maps each term onto concepts from other common automation toolchains. See Mental Models for the narrative explanation.

ISA-88 Term	Definition	CRD / Resource	Closest analog
Enterprise	The business entity responsible for one or more sites.	`Enterprise` (cluster-scoped)	Same term everywhere — the top-level business unit.
Site	A physical, geographical, or logical grouping of process cells.	`Site` (cluster-scoped) — creates namespace `site-{name}`	A plant or facility in most toolchains.
Area	A physical, geographical, or logical subdivision of a site containing process cells.	`Area` (namespaced)	An area or production line within a plant.
Process cell	A logical grouping of equipment required for the production of one or more batches.	`ProcessCell` (namespaced)	A batch cell or train — the set of units that cooperate on one batch.
Unit	A collection of associated control modules that performs one or more major processing activities (e.g. a reactor, a mix tank, a filter-dryer).	`Unit` (namespaced) — one runtime pod per unit	A reactor/mixer/dryer instance in a class-based DCS library, or an equipment instance in a PLC I/O tree. One pod per Unit runs the control logic.
Control module	The smallest addressable piece of equipment — a valve, a sensor, a modulating output, a PID loop.	`ControlModule` (namespaced); see Control Modules library	A reusable function-block wrapper: an AOI instance in a ladder/ST environment, or a device object in a class-based DCS library.

Procedural model¶

The procedural model defines what the equipment does. It is a four-level hierarchy mirroring the physical model.

ISA-88 Term	Definition	CRD / Resource	Closest analog
Procedure	The highest level of the procedural hierarchy — the strategy for making a batch. Executes against the process cell.	`Procedure` (namespaced)	The top-level recipe flow in a batch manager.
Unit procedure	A strategy for carrying out a contiguous production sequence within a single unit.	`UnitProcedure` (namespaced); templates under Operation & Unit-Procedure Templates	A unit-scoped subroutine that composes several operations; the layer just above 'phase' in most batch-manager software.
Operation	An ordered set of phases that take the material being processed from one state to another, usually involving a physical or chemical change (e.g. a CIP rinse operation).	`Operation` (namespaced); templates under Operation Templates	A subroutine that calls several phase routines in order. A reusable sub-sequence within a unit procedure.
Phase	The lowest level of the procedural hierarchy — drives a bounded action (fill, heat, agitate, drain, …).	`Phase` (namespaced); templates under Phase Templates	A parameterized routine, or a Phase Class in a class-based DCS library. By project convention each phase is authored as an SFC chart; the CRD also exposes bare-ST fields (`actionST`, `holdingST`, …) as a discouraged fallback (only the legacy `Logic` field carries a formal deprecation marker).

Recipe model¶

Recipes are the descriptive information needed to produce a specific product.

ISA-88 Term	Definition	CRD / Resource	Closest analog
Master recipe	Equipment-specific recipe bound to a process cell, ready to be scheduled.	`MasterRecipe` (namespaced); examples under Master Recipes	The equipment-bound recipe a batch manager actually schedules.
Control recipe	A runnable instance of a master recipe for a specific batch. Created automatically when a batch is scheduled.	`ControlRecipe` (namespaced, controller-generated)	The per-batch runtime copy of a master recipe generated at schedule time.
Batch	An entity that represents the material produced by a single execution of a control recipe.	`Batch` (namespaced)	A batch ID / batch object in a batch-execution system.

See Recipes for the cascade in practice and ISA-88 Traceability for the full requirement mapping.

Other resources¶

Resources outside the core ISA-88 physical/procedural/recipe hierarchy that still surface in the Web UI, CLI, and CRs.

Control logic¶

Term	Definition	CRD / Resource
Function block type	Reusable IEC 61131-3 function block definition (ST or FBD) available to unit runtimes.	`FunctionBlockType` (cluster-scoped)
Control module template	Reusable control-module blueprint bound to specific hardware at instantiation.	`ControlModuleTemplate` (cluster-scoped)
Control program	An ST/FBD program deployed to a unit runtime outside the phase hierarchy (e.g. background interlocks).	`ControlProgram` (namespaced)
Coordination block	Cross-unit synchronization primitive used by multi-unit recipes. Shipped in the full chart — see Architecture.	`CoordinationBlock` (namespaced)

Alarms, audit, change control¶

These resources carry the bulk of the 21 CFR Part 11 compliance surface.

Term	Definition	CRD / Resource
Alarm definition	Declarative alarm rule (condition, priority, message) attached to a control module or unit.	`AlarmDefinition` (namespaced)
Alarm	A live alarm instance raised by an alarm definition.	`Alarm` (namespaced)
Audit record	Immutable, HMAC-sealed record of an operator action or system event.	`AuditRecord` (namespaced) — archived to PostgreSQL by `audit-archiver`
Change control policy	Governs which CR kinds require an approval workflow before apply.	`ChangeControlPolicy` (cluster-scoped)

HMI, I/O¶

Term	Definition	CRD / Resource
IO module	A remote-I/O chassis/coupler (Modbus, EtherNet/IP, OPC UA) addressed by control modules.	`IOModule` (namespaced)
Controller	A device node enrolled into the control system — runs one or more unit runtimes.	`Controller` (namespaced)

Acronyms¶

Acronyms used throughout this documentation, grouped by topic. Expansions follow the standards body or common industry usage.

Standards, regulations & qualification¶

Acronym	Expansion	Notes
DCS	Distributed Control System	The product category Cloud-Native DCS targets.
ISA-88	ANSI/ISA-88.00 — Batch Control	Also published as IEC 61512. See ISA-88 Traceability.
ISA-95	ANSI/ISA-95 — Enterprise-Control System Integration	Defines the MES/control-system boundary. See MES Integration.
IEC 61131-3	Programmable controllers — Part 3: Programming languages	Source of ST, SFC, and FBD. See Structured Text.
IEC 61499	Function blocks for industrial-process measurement and control	Legacy reference; the project has migrated to IEC 61131-3.
IEC 62443	Security for industrial automation and control systems	See IEC 62443 Traceability.
21 CFR Part 11	FDA regulation on electronic records and electronic signatures	See 21 CFR Part 11.
IQ / OQ / PQ	Installation / Operational / Performance Qualification	Computer-system validation phases. See Executable Validation.
BPR	Batch Production Record	Defined by ISA-88 Part 4; exposed as `BatchRecord`.

Protocols, formats & infrastructure¶

Acronym	Expansion	Notes
MQTT	Message Queuing Telemetry Transport	Pub/sub protocol used for telemetry. See MQTT Telemetry.
OPC UA	Open Platform Communications — Unified Architecture	Industrial client/server protocol; one of the supported I/O drivers.
EtherNet/IP	Ethernet Industrial Protocol	ODVA-standard protocol for remote I/O.
Modbus TCP	Modbus over TCP/IP	Widely used remote-I/O protocol; default for Wago 750 couplers.
REST	Representational State Transfer	Gateway HTTP API style. See REST API.
gRPC	Google Remote Procedure Call	HTTP/2 RPC framework; used for gateway↔runtime health and control.
OTLP	OpenTelemetry Protocol	Trace/metric export format. See Monitoring and Metrics.
B2MML	Business To Manufacturing Markup Language	XML schema for ISA-95 exchanges. See MES Integration.
CRD	Custom Resource Definition	Kubernetes extension mechanism; every DCS resource type is a CRD.
API	Application Programming Interface	Also overloaded below as "Active Pharmaceutical Ingredient" in recipe contexts.
CLI	Command-Line Interface	The `dcs` binary. See CLI Reference.
UI	User Interface	The browser-based gateway front end.
HA	High Availability	See High Availability.
I/O	Input / Output	Signals to and from field devices.
k3s	Lightweight Kubernetes distribution	One of several Kubernetes distributions a deployment may run on; the product is distribution-agnostic.

Security & identity¶

Acronym	Expansion	Notes
OIDC	OpenID Connect	Web-UI authentication protocol. See Security Hardening.
RBAC	Role-Based Access Control	Kubernetes-native authorization model; DCS roles layer on top.
ACL	Access Control List	Per-topic MQTT authorization rules.
TLS	Transport Layer Security	Encrypted transport for all external endpoints.
mTLS	Mutual TLS	Both client and server present certificates; used on the internal bus.
HMAC	Hash-based Message Authentication Code	Tamper-evident seal on audit records.
SHA-256	Secure Hash Algorithm, 256-bit	Hash primitive used throughout the audit chain.
SIEM	Security Information and Event Management	External system that ingests DCS security events.
ESO	External Secrets Operator	Kubernetes operator that syncs secrets from an external vault.

Control, logic & process operations¶

Acronym	Expansion	Notes
SFC	Sequential Function Chart	IEC 61131-3 graphical language; by convention each Phase is authored as one SFC chart. See Phases.
FBD	Function Block Diagram	IEC 61131-3 graphical language for interconnected function blocks.
ST	Structured Text	IEC 61131-3 textual language. See Structured Text.
FB	Function Block	Reusable ST or FBD routine with internal state.
PID	Proportional-Integral-Derivative	Classical feedback controller; available as a `pid-loop` control module.
PLC	Programmable Logic Controller	Traditional industrial controller; Cloud-Native DCS plays this role in software.
SCADA	Supervisory Control And Data Acquisition	Upstream visualization tier. See SCADA Integration.
HMI	Human-Machine Interface	See the user-facing term above — specifically the `/hmi` operations endpoint.
MES	Manufacturing Execution System	Upstream order/recipe management tier. See MES Integration.
CIP	Clean-In-Place	Automated cleaning cycles. Example recipes under sim-cip-cycle-m1.
WFI	Water For Injection	Pharmaceutical-grade water used in reactor and tank simulations.
API (pharma)	Active Pharmaceutical Ingredient	The end product of an isolation recipe; do not confuse with HTTP API.

Guidelines¶

User-facing text (web UI, end-user documentation) should use control system. "Cluster" is the deprecated term there.
Developer-facing text (CONTRIBUTING.md, Go comments referencing Kubernetes API concepts, kubebuilder markers) may use "cluster" where it refers to the Kubernetes concept directly (e.g., scope=Cluster, "cluster-scoped CRD").
When both audiences overlap, prefer "control system" with a parenthetical note if the Kubernetes term is needed for clarity.