Generalized Capability Principles
draft-davis-nmop-generalized-capability-principles-01
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Nigel Davis , Camilo Cardona , Diego Lopez , Marisol Palmero | ||
| Last updated | 2026-03-01 | ||
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draft-davis-nmop-generalized-capability-principles-01
NMOP N. R. Davis
Internet-Draft Ciena
Intended status: Informational C. Cardona
Expires: 2 September 2026 NTT
D. Lopez
Telefonica
M. Palmero
Independent
1 March 2026
Generalized Capability Principles
draft-davis-nmop-generalized-capability-principles-01
Abstract
This document introduces a framework for capability modeling based on
the specification and refinement principles established in ITU-T
G.7711 Annex G (also previously published as ONF TR-512.7. See
latest G.7711 release) and the modeling boundaries work documented in
draft-davis-netmod-modelling-boundaries. The framework defines how
component–system capabilities can be explicitly described and refined
via a process of pruning, refactoring, and occurrence formation.
These capability definitions can target detailed operational
considerations, system interactions, licensing, abstract product
declarations, or sales and marketing. The framework supports
modular, layered, and fractal declarations of networked behavior, and
provides a foundation for a suite of future IETF drafts aligned with
ongoing work on photonic plug manifests, entitlement/licensing, IVY
equipment modeling, energy/thermal considerations and related
domains.
About This Document
This note is to be removed before publishing as an RFC.
The latest revision of this draft can be found at
https://github.com/marisolpalmero/draft-ietf-davis-generalized-
capability-principles/blob/main/draft-davis-nmop-generalized-
capability-principles-latest.md. Status information for this
document may be found at https://datatracker.ietf.org/doc/draft-
davis-nmop-generalized-capability-principles/.
Discussion of this document takes place on the Network Management
Operations mailing list (mailto:nmop@ietf.org), which is archived at
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https://www.ietf.org/mailman/listinfo/nmop/.
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Source for this draft and an issue tracker can be found at
https://github.com/marisolpalmero/draft-ietf-davis-generalized-
capability-principles.
Status of This Memo
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This Internet-Draft will expire on 2 September 2026.
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document authors. All rights reserved.
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 5
4. Specification in terms of the Model . . . . . . . . . . . . . 7
5. Generalized Modeling via Component–System–Specification
Refinement . . . . . . . . . . . . . . . . . . . . . . . 8
6. Specifications and LLMs . . . . . . . . . . . . . . . . . . . 10
7. Some specification examples . . . . . . . . . . . . . . . . . 11
7.1. A temperature sensor . . . . . . . . . . . . . . . . . . 11
8. Recursive pruning and refactoring . . . . . . . . . . . . . . 12
8.1. Thing to component . . . . . . . . . . . . . . . . . . . 13
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8.2. Component to specific termination point . . . . . . . . . 13
8.3. Further examples . . . . . . . . . . . . . . . . . . . . 15
9. Specification of an assembly . . . . . . . . . . . . . . . . 15
10. Generalization of the specification . . . . . . . . . . . . . 15
11. Characteristics of a language of specification . . . . . . . 15
12. Specification language options . . . . . . . . . . . . . . . 16
13. Building a specification structure . . . . . . . . . . . . . 16
14. A specification evolution example . . . . . . . . . . . . . . 16
15. A system specification example . . . . . . . . . . . . . . . 16
16. Broader Application of the Language . . . . . . . . . . . . . 16
17. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 16
18. Security Considerations . . . . . . . . . . . . . . . . . . . 16
19. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
20. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
20.1. Normative References . . . . . . . . . . . . . . . . . . 16
20.2. Informative References . . . . . . . . . . . . . . . . . 17
Appendix A. Appendix A: Interpretive Notes on Refinement and
Occurrence . . . . . . . . . . . . . . . . . . . . . . . 18
A.1. A.1 No Single Refinement Path . . . . . . . . . . . . . . 18
A.2. A.2 Occurrence at Every Layer . . . . . . . . . . . . . . 18
A.3. A.3 Sweating Out the Shape . . . . . . . . . . . . . . . 18
A.4. A.4 Classification Considered Harmful . . . . . . . . . . 18
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 18
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT"
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in the
document are to be interpreted as described in RFC2119}}.
The following terms abbreviations are used in this document:
* capability: What can be achieved by an individual item both alone
and in assembly (using the component-system pattern)
* needs: Related to capability, this is what the item, either alone
or in assembly, needs to achieve its capabilities
* manifest: A list of essential contents
* specification: A detailed definition of capabilities/needs in
terms of opportunities/constraints including the arrangement of
essential parts and their interconnectivity in assembly
* representation: An expression of structure and properties from a
perspective
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* component: A thing defined by a boundary where the internal
structure within that boundary is not directly visible but is
apparently visible through the behaviour exposed at that boundary
* port: A place on the boundary of a component where interaction
with that component is possible
* component-system: A pattern that expresses each item as a
component where components can be assembled into systems and where
a system can be represented as a component where that assembly may
be of real things or may be abstractions of the effect of real
things.
* occurrence: A thing, the specification of which is a purposeful
refinement partially constraining the definition of a broader
thing, where a thing is a component, a specification etc.
* pruning: A process of narrowing of definition by reduction of
capabilities
* refactoring: A process of rearranging, splitting and combining
representation whilst maintaining semantic validity
* pruning & refactoring: The process that supports intentional
progression of refinement from one level of structure of
occurrences (e.g., system of components) to the next more specific
level of structure of occurrences
2. Introduction
Currently, capabilities are mainly described loosely in human
readable text, where that text is often incomplete, ambiguous or
inconsistent. While people make these systems work in practice, the
looseness result in errors, inefficiencies and limited reuse. As
automation increases, there is a growing need to enable machine
reasoning about the capabilities of network systems and components.
While Large Language Models (LLMs) can interpret traditional
documentation, there remains a strong need for greater formal rigor
and structured representation to improve efficiency and precision.
When asked, LLMs indicate that a rigorous model is preferable to
loose ambiguous text. Existing IETF models predominantly focus on
configuration, operational state, and telemetry. What is missing is
a cohesive framework for expressing what a system _can_ do, i.e., its
capabilities, in a declarative, structured, and reusable form. This
document introduces the principles for a capability modeling
framework grounded in the specification concept established in
[ITU-T_G.7711] ([ONF_TR-512]). It applies these principles through
the lens of the *component–system pattern* from [ONF_TR-512.A.2],
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using the concept of *emergence through recursive narrowing,
refactoring and occurrence formation*. These ideas are extended
further by the modeling boundary principles described in [mobo]. The
result is a standardized and extensible approach for expressing
features, operational constraints, internal dependencies, etc. -
separately from instance realizations. This approach supports
capability modeling for any aspect of the controlled networking
solution, and is designed to enable capability assembly, dynamic
composition, licensing control, and integration with other IETF
frameworks such as IVY equipment, photonic plug manifests, and
entitlement interfaces. It also supports initiatives focussing on
energy/thermal considerations where specific detailed capabilities
and their power/thermal implications become critical considerations.
3. Problem Statement
Network technologies and management-control frameworks increasingly
rely on declarative data models to represent both configuration and
operational state. However, these models often lack a principled way
to describe the _capabilities_ of components and systems—what they
are able to support or provide, independent of any particular
operational instance. This omission makes it difficult to reason
about compatibility, constraint satisfaction, composition, or even
basic intent feasibility. Clearly, many of these activities take
place prior to the installation of the equipment and indeed determine
which equipments are to be planned to be installed. In these cases
it is not possible to interogate the actual equipment. Whilst
knowing the YANG model for the equipment is beneficial, it is not
sufficient as the YANG model essentially provides a space within
which actual state etc. can be expresses, but it supports all
possible combinations. The equipment will be very limited in
comparison. Often it is desirable from a systems operation
perspective to reduce the available capability through policy or
other mechanisms due to the restrictions of a specific role. This
becomes challenging if the base capability of a component is unclear
and expressed in a chaotic form. In practice, five distinct concerns
are often conflated, and also not fully expressed, within data
models: - The *generic definition* of a model element or concept
(e.g., a termination point) - this is expressed in YANG. It is a
very broad definition encompassing all possible opportunities and
ofthen many illegal state combinations etc. - The *capability
definition* of a system or component, i.e., what it can support or
expose (e.g., by a specific type or role of termination point). This
is not expressed fully in YANG. There are both challenges with the
expression of base capability and expression of the capability of
combinations. This is especially sparce in representation - The
users *policy definition* for system operation - the user may
eliminate particular capabilities due to complexity, lack of trust,
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regulation etc. and will not want them offered or may not want them
offered under certain circumstances. The equipment will be expected
to behave as if it does not have the capabilities as approproiate. -
The *system combination* where an entity type may play several
different roles and in each role may have specific distinct
intentional limitations/restrictions. - The *operational
instance*—what is configured or active at a given time. Without a
clear structural separation and with the sparseness of information on
specific capabilities, it becomes challenging to formally describe
feature constraints, support boundaries, or internal limitations.
Implementers resort to informal documentation, code comments, yellow
stickies, or out-of-band agreements to capture the intent behind
model behavior. This reduces interoperability, increases integration
effort, and undermines automation as a result of - *Ambiguity*
between what a model element _is_ versus what a system _can support_.
- *Redundancy* and inconsistency in the representation of common
constraints (e.g., port types, layering, resource limits). - *Tooling
difficulty* when extracting interoperable subsets of large models or
generating technology-specific profiles. - *Incompatibility* between
modular subsystems or plug-ins that must declare and verify their
supported features. Furthermore, current models tend to assume a
fixed taxonomy of types and features, rather than supporting a
process of recursive refinement. This limits their ability to
express how complex capabilities _emerge_ through constraint,
composition, and modular pruning of more general-purpose constructs.
What is needed is a modeling framework that: - Allows systems and
components to be described in terms of their *capability boundaries*,
including *capability interactions* separate from operational state,
- Supports *refinement via pruning and refactoring to yield flexible
structural transformation* rather than rigid inheritance or
classification, - Enables *recursive occurrence formation*, where
each level of pruning and refactoring produces a usable semantic
structure, - Accommodates *multiple valid refinement paths*,
supporting different levels of granularity and domain specificity, -
Provides a *coherent trace* from abstract capability declarations
down to deployable or licensable configurations. This draft
introduces such a framework by building on the refinement logic of
[ITU-T_G.7711] ([ONF_TR-512]) in general and especially the
*specification pattern* structures of ITU-T G.7711 Annex G (ONF
TR-512.7) which provides a means of expressing bounded capability
envelopes through a formal refinement of generic model elements.
This also provides grounding in the recursive occurrence model
informed by the component–system pattern [ITU-T_G.7711]
([ONF_TR-512.A.2] and modeling boundaries approach [mobo]. This
document leverages the foundations laid by [ITU-T_G.7711]
([ONF_TR-512]).
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The same expression challenges appear in statements of intent. The
process of formulating intent through negotiation and resultant
gradual refinement has a similar feel to the degrees of pruning and
refactoring of the specification.
4. Specification in terms of the Model
The specification of capability should be presented in terms of the
terminology of the problem space and hence in terms of the
appropriate model. The challenge is determining which model is the
"appropriate" model.
An area of the problem space can be described in different ways
depending upon what the intention of the model is. There are many
ways of representing a semantic space/
Prior to embarking on evaluation of specification of capability, it
is important to consider the specific model and how it is structured.
* Focus: Semantic area covered at centre and periphery
* Specialization: Specific detailed focus on an area with rich
structure, e.g., PCE, problem analysis, etc.
* Granularity: the “size” of the semantic units (including the depth
of recursion of fractal representations)
* Phase: The positioning of the semantic boundaries
* Richness: The detailed coverage within a semantic unit
* Fidelity: Precision v approximation
* Abstraction: Closeness to actual detail
* Maturity: Lifecycle development stage. How stable the model is
likely to be. This is primarily about semantics, but also covers
syntax.
* Omission: Gaps and missing parts
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5. Generalized Modeling via Component–System–Specification Refinement
This framework moves away from rigid classification schemes and
instead adopts a dynamic, refinement-based approach to modeling.
Traditional classification attempts to impose fixed categories onto a
system, but this often obscures nuance, variation, and the emergence
of intermediate structures that carry operational or architectural
significance.
We begin instead with the concept of a *universal component*—a
general-purpose structure with maximal capability potential. Through
the process of *pruning & refactoring* (constraint-driven
refinement), this semantic volume is gradually refined, yielding
intermediate structures with more sharply defined roles and
properties. These refined artifacts are not pre-classified entities,
but *emergent forms* that arise naturally at specific “sweat spots”
in the refinement trajectory, where the remaining capabilities align
with a recognizably useful or interoperable function.
Each such emergent form is treated as an *occurrence*. Occurrences
appear at every stage of meaningful refinement including at the level
of final implementation instances. At all stages of use the
application of properties is via the idea of intent where even the
tightest constraint of a single value is essentially a statement of
intent (as it is impossible to guarantee that a property will be
set). This intent consideration will be dealt with further later in
this document.
An LTP (Logical Termination Point) in [ITU-T_G.7711] ([ONF_TR-512]),
for example, is not a primitive class but a pattern that arises from
pruning and constraining the universal component until only the
semantic envelope of an LTP remains. A TerminationPoint from RFC8345
To support variation, reusability, and convergence across
implementations, each component or system is described not by a
single fixed class, but by a *specification*: a constrained and
possibly pruned refinement of a more general and broader model
element. This allows the model to express bounded capabilities
without requiring full instantiation, enabling tools and
orchestrators to reason about compatibility, substitution, and
support constraints before deployment. The specification describes
the capabilities of an occurrence in terms of occurrences achieved
via similar pruning. A system spec is a pattern assembly of subtly
specialized occurrences at a particular level of specialization
arranged in a meaningful structure that yields a relevant behaviour.
The specification of an occurrence is itself a system spec.
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The combination of the *component–system pattern* with the
*specification refinement pattern* enables a modeling architecture
where:
* Systems are recursively composed of components,
* Specifications constrain and refine capabilities at each level,
* Occurrences are layered realizations of specs applied to specific
contexts or configurations.
This approach supports *gradual realization*, where capability
declarations can progressively transition from abstract to concrete,
through intermediate spec refinements and pruning. Each layer of
model realization adds specificity—structurally (via system
composition), behaviorally (via constraints), and operationally (via
mapping to configuration/state models).
A specification may provide explicit definifinition of a property as
discussed above but it may also refer to one or more other
specification(s). For example a specification may include a set of
properties specified elsewhere. It may also define a property that
is an enumeration of literals or identifies where those literal
values or identify values are actually references to other
specifications that provide deeper detail.
In an ideal environment, there is an ecosystem of specificactions
each providing interrelated detail to fully define the semantics.
The ecosystem would include specifications from standards bodies
providing the definition of a network protocol that can be
interpreted by an AI component such that the abstracted effect on the
solution can be fully understood and simulated/emulated. Any
detected conditions would be understood in terms of the protocol and
hence the implications of the condition detected in terms of the
carried signal can be fully understood.
In this ideal environment, the specification would fully capture all
non-failure case behaviours of a component (and potentially some
common failure cases) and the component would be designed internally
to "guarantee" these behaviours (it would be engineered with
appropriate control structures that would bound its behaviour).
These specifications, although abstractions would often be highly
complex (consider the specification of a CPU for example), but would
be less overwhelming in detail and stated in terms of intentional
behaviour as opposed to behaviour of the parts. The specification is
a statement of the effects of the assembly of detailed parts (see
definition of component).
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The specification of capability provides a stabilising layer reducing
the reasoning required to build a solution as a result of not having
to assess the full detail of behaviour of all assemblies to the
finest detail. The specification of capability will have a unique
identifier that anchors the definition and allows it to be accessed.
This reflects the same principle that gives rise to labels in a
taxonomy, where the label recalls the abstract definition removing
the need to understand the effect of the parts from first principles.
Today's solution at best have a coded form of the semantic
interpretation that may not reflect the formal definition due to
inaccuracies of interpretation. Many semantics are reduced to
inconsistent labels that a user has to interpret. Whilst an LLM can
do a reasonable job at interpretation of chaotic data, it will
benefit a rigorous model traceable through formal definitions to
fundamentals.
6. Specifications and LLMs
As discussed briefly above, LLMs can take advantage of specifications
of capability. The LLM reasoning load can be reduced by working with
the guaranteed behavioural abstraction provided in the specification
for a component as opposed to working at the finest of details (it
does not always need to understand the environment using string
theory!).
The LLM can develop system solutions by assembling components of
understood capability (using normal engineering and design processes)
knowing that the behaviour of the components are internally
controlled to be within the bounds of the specification. The LLM can
then describe the behaviour of the system at its boundaries, i.e., of
the component(s) that that system can realize. Hence the LLM can
develop the specification for the components it produces.
For components not produced by a specific LLM (produced by another
LLM or by a human), the LLM can assess the internal workings of the
component (by reviewing the actual code/circuitry) at fine-grained
detail. LLM reasoning can:
* extract the essential behaviour and abstract that to form a
specification
* consider whether that abstracted behaviour defined in the
specification appears beneficial in the formation of relevant
systems and where not, propose simplifications
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* evaluate the robustness of that essential behaviour and propose
enhancements to ensure that the component operates within the
desired bounds
* review existing specifications to determine whether other
components already do a similar job
* etc.
7. Some specification examples
This section provides some simple examples and will reference the
equipment capability draft and other future drafts.
7.1. A temperature sensor
Consider a simple temperature sensor. The physical sensor will have
an operational range, a precision, an accuracy, etc. It will provide
output in particular units and may be able to indicate out of range.
The sensor is itself a small system of components. It will be
sensitive to power supply behaviour, humidity and other environmental
factors.
All of the above will be included in the hardware specification of
that physical component. That component when designed into a system
will contribute to the system behavior.
For this example we will assume that the output for that sensor is
available via a control solution and is presented at an externally
accessible interface. We will assume that the presentation is in
JSON and that presentation was defined in YANG.
In a the imagined application for this sensor, lets assume that the
temperature is relevant only to whole degrees and is required to be
in Celsius so an integer is used to represent the temperature.
With this level of coarseness the fine grained precision and accuracy
of the actual component can probably be ignored (although the
component may be pushed close to its limits and hence there may be an
accuracy consideration etc.), but the operational range is
potentially still relevant and environment effects that cannot be
eliminated still need to be understood.
There may also be known failure modes that cause detectable incorrect
readings that need to be accounted for.
So, considering the component alone, simply stating integer in the
YANG model is not sufficient.
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Going further, the temperature sensor has a particular role in the
context of the equipment it is monitoring. There may be several
temperature sensors on that single equipment. Traditionally they
would have had distinct labels (although these were often potentially
misleading). Whilst this may have been sufficient in a basic
operations environment, much more can be done and is probably
necessary current and future solutions.
Having an identifier is clearly necessary, but that should lead to an
accurate and fully interpretable representation of the positioning of
that component in the equipment in isolation and in the broader
solution as a whole.
For example, the detector may be at the top of a circuit pack that is
placed in an assembly with convection cooling where that detector is
provided to measure the temperature of the airflow leaving the top of
the circuit pack and hence feeding to the next equipment above.
For a full understanding of the implications of a measurement
provided by that detector, a detailed understanding of its
positioning and purpose is necessary. It is intended that the
specification model provide such detail.
The specification model will be generalized such that the details
provided can be used in any relevant application. It will not
describe detailed per instance cases. Hence the specification will
be used in conjunction with the actual instance arrangement to allow
understanding of any reading in context.
Traditionally, with ad-hoc formatting and variable accuracy of
definitions etc., only a well experienced SME would have a chance of
determining the relevance of a detected value.
In a modern and future solutions we can do and have to do better.
The intention is that the specification approach using the
generalised specification definition structure set out in this
document will provide a basis for LLM assisted specification
generation and interpretation.
8. Recursive pruning and refactoring
This builds on the example sketches and formalizes the process of
recursive pruning and refactoring.
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The essential process involves defining a general abstracted thing at
some intermediate point in the progression of refinement (e.g., a
temperature sensor), setting out a reasonable derivation path from
the most generalized component and then refining that general
abstract thing by recursive pruning and refactoring to arrive at the
necessary specialization.
The following subsections take some generalised cases to illustrate
the process.
8.1. Thing to component
In this approach a thing has all possible functions and capabilities
of anything imaginable. Moving to component via pruning and
refactoring involves recognition of the concept of boundary of a
thing and then facet of a boundary, i.e., a surface that can
"interface" with the surface of another thing. From facet, we can
derive port which is a specific place on the surface where an
interface can be formed. The idea of port is fundmental in the
essence of a component as it is the place where the component
capabilities are accessed.
The same essential approach can be used to move from assembly of
things being a thing to the more formalised component system pattern.
A component can be physical or abstract functional. All components
have some active influence on their environment (unlike a
specification which is an informational thing and is inherently
passive). The generalized abstract functional component is a pruned
form of the generalized component. It includes all possible
behaviours. It is still too general to apply meaningfully and
requires further pruning.
8.2. Component to specific termination point
A termination point as per [RFC8345] is a specific pruned functional
component that offers at its ports a defined subset of all possible
functions. It does not offer the capability to forward information
over great distances but does offer the ability to provide access to
a flow of information at a specific place. In other standards [ITU-T
G.7711] the LogicalTerminationPoint has roles including in one
direction processing an incoming flow determining timing and framing
and extracting the content "payload".
The termination point is still general and requires refinement to
represent what is really feasible and useful in a network deployment
context.
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Up to this point refinement was carried out via pruning and
refactoring where each level resulted in an explicit relabelling
Thing -> Component -> TerminationPoint. Traditionally, the same
orientation of progression was considered as a process of
classification where properties were added as opposed to removed and
the process continued beyond this point to highly specialised
classes.
In the approach realized via [RFC8345] and [ITU-T G.7711], further
refinement is carried out by augmentation. Here augmentation
essentially exposes properties that were already encompassed by the
definition of the thing being augmented. It is not an extension, it
is an exposure of underlying properties.
So a termination point that processes photons is represented via an
augmentation of the generalised termination point. Likewise, the
termination point that process Ethernet is represented via an
equivalent augmentation. Clearly, an augmentation of a termination
point with photonic and Ethernet properties is not rational.
This is where the specification becomes critical. Each specific
realization of a termination point type in software or hardware will
be distinct. Just because it is an Ethernet termination point type
does not mean it is the same as all other Ethernet termination point
types. Of course, there will be many many instances of the type and
they will have identical functional capability.
Setting out the distinct capabilities of the type is the role of the
specification. The specification will be constructed by assembling
pruned and refactored specifications of more complete definitions.
So, for example, the Ethernet standard may define MEP and MIP
capabilities, but the type of termination point may only support MEPs
and there may be 7 levels of MEP in the standard, but this
termination point type may only support 1 level where the
measurements available to the MEP may be limited and a specific
measurement constrained in range. All of this detail is available
via the specification.
Armed with the specification a controller can determine precisely how
the termination point can be applied in a solution and the range of
opportunities available.
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Whilst designing a solution, the controller may use a specific type
of termination in a restricted form. For example, the Ethernet
termination, although capable of supporting a MEP may be required to
not provide that capability. The design of the pattern of use of
terminations in a system may utilise the same type several times in
the pattern where each occurrence in the pattern has a distinct
further narrowing of the capability of the type. This is discussed
further in Specification of an assembly (add reference to section).
Eventually the pattern will be realized in a network. This will
first be designed with no real instances in place. This will be
represented with further specific narrowed termination point
occurrences. Finally, there will be real instances in the network.
These can also be considered as occurrences.
8.3. Further examples
-Thing to Component to physical thing to equipment to specific
equipment type to use of that equipment to instance of equipment -A
plug example Circle back and relate this more rigorous section to the
specification examples.
9. Specification of an assembly
Build on the examples and the recursive pruning and refactoring to
explain the subtle narrowings in a system/scheme spec. Describe the
essential process. Use examples to illustrate the progression: -
Same examples as recursive pruning and refactoring but focus on role
and subtle specializations in role List other examples.
10. Generalization of the specification
Build a specification structure from the examples and show the
references and reuses. Explain how the specification relates to the
things in the problem space. Lay out the specification structure.
11. Characteristics of a language of specification
The language needs inherent capabilities (as opposed to after the
fact bolt-on warts) Extract key characteristics from above and from
mobo - narrowing requires specific redefine (relate to pruning) -
occurrence is an assembly of constrained type and specific values -
need to reference other specs as reusable parts - refactoring, minor
specialization and assembly - interrelationship and influence -
uncertainty and preferences (Need to review mobo and TR-547 spec,
component-system etc.)
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12. Specification language options
Landscape of languages... does anything do this? Take YANG and
enhance (as discussed in mobo)
13. Building a specification structure
Tooling and support to build and interrelate. Catalogue/library of
specs Deep application... machine interpretable structure in all
standards Use of AI to reverse engineer specs with guidance... peer
review and testing cycle
14. A specification evolution example
Discuss how a spec may change as understanding emerges and how it may
be refactored.
15. A system specification example
Take the language considerations and set out system specs in a more
formal way
16. Broader Application of the Language
Negotiation Refinement of planning Development of standards
Expression of uncertainty and pattern
17. Conclusion
Mindset Change Language challenges Use of AI Target is an ecosystem
of specs driving agentic components...
18. Security Considerations
TBD
19. IANA Considerations
This document has no IANA actions.
20. References
20.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
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[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
20.2. Informative References
[BaseInventory]
Yu, C., Belotti, S., Bouquier, J., Peruzzini, F., and P.
Bedard, "A Base YANG Data Model for Network Inventory",
Work in Progress, Internet-Draft, draft-ietf-ivy-network-
inventory-yang-14, 5 February 2026,
<https://datatracker.ietf.org/doc/html/draft-ietf-ivy-
network-inventory-yang-14>.
[ITU-T_G.7711]
"Generic….", 31 August 2022, <https://www.itu.int/rec/T-
REC-G.7711/recommendation.asp?lang=en&parent=T-REC-
G.7711-202202-I)>.
[ivy] "ivy", 31 August 2022, <https:// 3.pdf>.
[LF_TAPI] "Transport API", n.d., <https://github.com/Open-Network-
Models-and-Interfaces-ONMI/TAPI-Home>.
[mobo] "draft-davis-netmod-modelling-boundaries", 31 August 2022,
<https:// 3.pdf>.
[ONF_TR-512]
"TR-512 Core Information Model (CoreModel) v1.5", n.d.,
<https://opennetworking.org/wp-content/uploads/2021/11/TR-
512_v1.5_OnfCoreIm-info.zip>.
[ONF_TR-512.7]
"TR-512.7 Specification", n.d.,
<https://opennetworking.org/wp-content/uploads/2021/11/TR-
512_v1.5_OnfCoreIm-info.zip>.
[ONF_TR-512.8]
"TR-512.8 Control", n.d., <https://opennetworking.org/wp-
content/uploads/2021/11/TR-512_v1.5_OnfCoreIm-info.zip>.
[ONF_TR-512.A.2]
"TR-512.A.2 Appendix: Model Structure, Patterns and
Architecture", n.d., <https://opennetworking.org/wp-
content/uploads/2021/11/TR-512_v1.5_OnfCoreIm-info.zip>.
[plug] "plug", 31 August 2022, <https:// 3.pdf>.
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Appendix A. Appendix A: Interpretive Notes on Refinement and Occurrence
A.1. A.1 No Single Refinement Path
In this modeling approach, there is no single correct way to refine a
universal component. The refinement process supports multiple valid
paths, each representing a different semantic purpose, level of
granularity, or domain context. What emerges depends not on a fixed
taxonomy, but on the alignment of constraints, intent, and reuse
patterns.
This enables: - Coexistence of multiple specification layers derived
from the same abstract element, - Domain-specific “semantic phases”
that are meaningful within a particular stack (e.g., optical vs
packet), - Purpose-driven modeling: e.g., one path for plug
manifests, another for logical topology.
A.2. A.2 Occurrence at Every Layer
Occurrences are not limited to final instances. Each meaningful
stage of refinement produces an occurrence—an intent-aligned,
constrained projection of the universal component. Even so-called
“instances” are not full realizations, but expressed intent within a
given operational context.
A.3. A.3 Sweating Out the Shape
Useful structural forms (e.g., an LTP) are not pre-classified
primitives. They _emerge_ from the pruning process when remaining
capabilities reach a “sweat spot” of balance—enough constraints to be
meaningful, but not so much as to be frozen. This allows the model
to remain adaptive while still supporting mapping, reasoning, and
automation.
A.4. A.4 Classification Considered Harmful
Rigid classification schemes tend to obscure natural emergence and
lead to artificial separations. This model rejects top-down typing
in favor of bottom-up capability surfacing, grounded in refinement
logic. Semantic rigor replaces taxonomic rigidity.
Appendix B. Acknowledgments
This document has been made with consensus and contributions coming
from multiple drafts with different visions. We would like to thank
all the participants in the IETF meeting discussions.
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Contributors
Nigel Davis
Ciena
Email: ndavis@ciena.com
Authors' Addresses
Nigel Robert Davis
Ciena
Email: ndavis@ciena.com
Camilo Cardona
NTT
Email: camilo@gin.ntt.net
Diego Lopez
Telefonica
Email: diego.r.lopez@telefonica.com
Marisol Palmero
Independent
Email: marisol.ietf@gmail.com
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