Technical data glossary: 73 terms from PDM, PLM and CAD

A – C

3DEXPERIENCE

Dassault Systèmes' platform bringing design, data and collaboration together, cloud or on-premise. A natural continuation for a shop already on SOLIDWORKS or CATIA — but a paradigm change, not an upgrade.

ACIS (.sat)

A geometric kernel competing with Parasolid, and its associated exchange format. As with Parasolid, exchange is more faithful between two tools built on the same kernel than through a neutral format.

AP203 / AP214 / AP242

The application protocols of the STEP standard. AP203 carries geometry and assembly structure, AP214 adds colours and layers, AP242 merges both and additionally carries model-based tolerancing. Ask for AP242 by default — the differences in detail here.

Approval

The transition moving a document to the approved state, by someone entitled to do it. It authorises release to production — and its traceability is the first thing an auditor asks for.

Check-in

The operation that returns a file to the vault after editing: it releases the lock and creates a new version. The opposite of check-out. A file left checked out over the weekend blocks everyone on Monday.

Item

The basic managed object of a PLM: a unique reference designating a part, an assembly, a purchased component or a consumable. Not to be confused with the file that describes it — an item can exist without a CAD file, and several files may describe one item.

Assembly

A CAD file positioning components relative to one another through mates. It doesn't contain its parts: it points at them, hence the importance of reference management.

B-Rep

Boundary representation: how a modeller describes a volume through its faces, edges and vertices. It's what STEP and Parasolid carry — exact geometry, without the history that produced it.

Local cache

The working copy of vault files on the user's workstation. It's what creates the feeling of speed — and a poorly purged cache is a classic cause of slowness and display inconsistencies.

Data card

The form attached to each file in a vault: description, material, revision, customer, project. It feeds BOMs and title blocks. Golden rule: closed lists rather than free text, otherwise the data becomes unusable within months.

CAD

Computer-aided design: 3D modelling and drafting software. CAD produces the geometric definition; PDM manages it; PLM places it within the product lifecycle.

Part numbering

The rules for assigning part identifiers. A good system is short, non-meaningful, non-reusable and automatically assigned — talking codes always backfire the day a part changes family. The full method.

Vault

The PDM-managed space where files live, with their history, metadata and links. The difference from a network folder: a folder stores files, a vault understands what it stores.

Configuration (SOLIDWORKS)

A variant of a part or assembly defined inside the same file: different lengths, options present or not. Convenient, but treacherous for BOMs — each configuration must map to a distinct item if it's bought or built separately.

Mate

The geometric relation positioning one component relative to another. Redundant mates, or mates on unstable entities, are a major cause of slowness and errors in large assemblies.

Batch conversion

Automatic processing of many files at once: bulk PDF or STEP export, property updates, printing. Essential during a migration, and reserved for advanced PDM editions.

CSWA / CSWP

Official SOLIDWORKS certifications, associate and professional level respectively. Useful when hiring to objectify a skill level; they don't replace experience with real assemblies and badly organised data.

D – I

Digital thread / digital twin

The digital thread is the continuity of information across the lifecycle; the digital twin is a digital replica of a product in service, fed by real data. Two heavily marketed terms: ask to see the data actually flowing before believing either.

Permissions

What each user may see, edit or move to the next state inside a vault. Permissions must technically forbid manipulations outside the vault — a verbal instruction never holds.

DXF / DWG

2D formats from the AutoCAD world. DXF remains the universal language of cutting machines: it's what you send for a sheet-metal flat. Always check units and scale before sending.

eBOM

The engineering bill of materials: the product structure as designed, usually derived from the CAD assembly. It always differs from the manufacturing BOM, and believing otherwise causes most gaps between engineering and production. Line-by-line example in eBOM vs mBOM: the difference.

ECR / ECO / ECN

The three phases of a change: the request (ECR), the order once impact is assessed and the decision taken (ECO), and the notice that releases the change (ECN). Many companies have only the third — and that's exactly the problem.

eDrawings

A free viewer that opens SOLIDWORKS parts, assemblies and drawings, with measurement and annotation. Many companies pay for full licenses for people who only need this.

ERP

The system that manages execution: purchasing, stock, work orders, invoicing. The boundary with PLM comes down to this: PLM defines the product, ERP executes it. The BOM runs between them.

State

A document's position in its workflow: in design, under review, approved, obsolete. Each state carries its own permissions — that's what keeps the shop floor off unapproved drawings.

Requirement

What the product must satisfy: performance, standard, customer constraint. In a mature PLM, each requirement is traced to the parts that fulfil it — the foundation of compliance files.

Check-out

The operation that reserves a file for editing: others see it read-only and know who holds it. It's the mechanism that eliminates mutual overwrites and diverging parallel copies.

Native / neutral format

Native holds all your work, feature tree included; neutral (STEP, Parasolid, IGES) carries only the geometric result. Simple rule: native to modify, neutral to manufacture.

Routing

The sequence of operations needed to make a part, with work centres and times. It lives on the methods and ERP side, and is one reason the manufacturing BOM differs from the engineering one.

GD&T

Geometric dimensioning and tolerancing: the standardised way of expressing form, orientation and position tolerances. Traditionally carried by the drawing, and by the model itself in an MBD approach.

IGES

An exchange format inherited from the 1980s, carrying often-unstitched surfaces — hence those fragmented imports you must repair. Use only if your counterpart genuinely can't read anything else.

Revision level

The mark of an approved, released state: A, B, C. It changes as soon as a document that went to production evolves. Not to be confused with the version, which traces work in progress.

ISO 10303

The international standard behind the STEP format. That open-standard status is what makes it the right choice for long-term archiving: it stays readable without depending on a vendor's survival.

J – P

Milestone

A formal checkpoint in a product project: design review, definition freeze, production launch. In a PLM, a milestone often gates a set of documents moving to the approved state.

JT

A lightweight visualisation and review format (ISO 14306), widespread in automotive. It lets very large assemblies circulate without distributing exact geometry.

Floating (network) license

A license shared by a server across several workstations, instead of being tied to one machine. Suited to teams where not everyone designs at once; it does require the license server to be reachable.

Digital mock-up (DMU)

The complete 3D representation of an assembled product, used for reviews, interference checks and assembly ergonomics — without a physical prototype.

mBOM

The manufacturing bill of materials: the product as actually assembled, with consumables, routings and intermediate assemblies. Building it from the eBOM is the classic friction point between engineering and methods — the full chain is detailed here.

MBD (model-based definition)

An approach where the 3D model itself carries the full definition — tolerances, surface finishes, notes — instead of deferring to a drawing. It assumes the recipient can exploit PMI, which is worth confirming before dropping drawings.

MES

The manufacturing execution system: what happens on the shop floor, machine by machine, in real time. Downstream of the ERP, which is itself downstream of PLM.

Metadata

Information about the file rather than in its geometry: description, material, revision, author, state. It makes search possible and BOMs usable — and it's what neutral formats almost always lose.

Migration

Transferring an existing file base into a new system. Its duration depends far more on data condition than on volume: a clean base of 200,000 files migrates faster than a messy one of 50,000 — full method.

Drawing

The 2D document carrying dimensions, tolerances and annotations for a part or assembly. It references the 3D model: renaming that model outside the vault empties its views.

Dumb solid

A solid imported without a feature tree: the geometry is exact but there are no parameters or history left. You edit it by direct modelling — offset a face, remove a hole — but you can no longer "change the dimension".

Bill of materials (BOM)

The structured list of everything a product is made of. It's the most sensitive object in the whole chain: it travels from engineering to purchasing and production, and any error propagates as far as the supplier order.

Geometric kernel

The engine that actually computes solids inside a modeller — Parasolid, ACIS and a few others. Two tools sharing a kernel exchange geometry with a fidelity no neutral format matches.

Obsolete

The state of a document withdrawn from circulation but kept for history. Marking obsolete rather than deleting is the rule: one day you'll need to prove what was delivered.

Pack and Go

A SOLIDWORKS function that gathers an assembly, its parts and its drawings into one consistent bundle. It's the right way to send a complete set to someone — far better than hand-copying files.

Parametric

Said of a model whose geometry derives from editable dimensions and relations: change a value and the part rebuilds. It's what you lose when going through a neutral format.

Parasolid (.x_t, .x_b)

Siemens' geometric kernel, used by SOLIDWORKS, Solid Edge, NX and Onshape among others — and its associated exchange format. Between two tools on the same kernel it's the most faithful transfer, and an excellent plan B when a STEP arrives damaged.

PDM

Product Data Management: managing design files — versions, rights, references, search — for the design office. It's the first building block, and often the only one an SME needs. The complete guide.

PLM

Product Lifecycle Management: managing the product definition across its whole lifecycle, from idea to withdrawal — items, BOMs, changes, requirements, compliance. It concerns the whole technical enterprise, not just engineering. The complete guide.

PMI

Product Manufacturing Information: tolerances, surface finishes and datums carried by the 3D model itself, in a software-readable form. It's STEP AP242's major contribution and the foundation of MBD.

Custom property

An information field stored in the CAD file: description, material, revision, supplier. It feeds title blocks and BOMs. Left as free text it becomes unusable; controlled by a list, it becomes an asset.

Q – Z

Rebuild

Recomputing the model after a change. A normal rebuild handles only what changed; a forced full rebuild (Ctrl+Q in SOLIDWORKS) recomputes everything and surfaces errors a normal rebuild leaves asleep.

External reference

A file's link to another: an assembly to its parts, a drawing to its model. An assembly doesn't contain its components, it points at them — which is why moving a file outside the vault breaks everything.

Replication

A mechanism keeping a synchronised copy of the vault at a remote site, so distant users work at local speed. It's one of the main reasons to move to the Professional edition.

Revision vs version

The most widespread confusion in the field. A version is created at each check-in and traces the work; a revision marks an approved, released state. You may have twelve versions between revision A and revision B.

RoHS / REACH

European regulations on hazardous substances in products. They require knowing, material by material, what each part contains — a traceability requirement that alone justifies many PLM projects.

Solid / surface modelling

Two modelling approaches: solid modelling manipulates closed volumes, surface modelling builds skins that are then stitched. Surfacing dominates automotive and aerospace for complex shapes; that's where CATIA and NX pull ahead.

SQL Server

The database storing a SOLIDWORKS PDM vault's metadata: who holds what, which versions exist, what values the cards carry. Small in volume but constantly queried — the first place to look when the vault slows down.

Skeleton

A design method where a master file carries the reference geometry components depend on. It makes large assemblies drivable, provided it's set up from the start.

STEP

The reference exchange format in mechanical engineering, standardised as ISO 10303. Always specify the protocol: "STEP" doesn't say whether you're getting colourless AP203 or AP242 with tolerancing.

STL / 3MF

Mesh formats for 3D printing. STL is just a set of triangles — no units, no colours, no precision beyond the mesh. 3MF, its modern successor, carries units, colours and materials. Neither is suitable for machining.

Over-defined

The state of a sketch where dimensions and relations contradict each other. The useful reflex: look at the automatic relations created while drawing, not at the dimensions you just placed.

Scheduled task

An automatic process launched by the vault: PDF conversion on approval, printing, property updates. Reserved for the Professional edition, and often what triggers the move to it.

Teamcenter

Siemens' PLM, the reference among large automotive and aerospace groups, with very broad functional coverage. Rarely the right pick for a standalone SME.

Toolbox

SOLIDWORKS' library of standard components — fasteners, bearings, profiles. Classic trap: each workstation keeps its own local copy, references diverge, and BOMs go wrong. One shared library, writable by a single owner.

Traceability

The ability to demonstrate who did what, when, and on which version. Required by ISO 9001 and sector regulations, it's nearly automatic in a vault and very expensive to reconstruct in a shared-folder organisation.

Variant

A product declination by options or dimensions. Well managed, it avoids duplicating the same design a hundred times; badly managed, it produces unmanageable item catalogues. It's one of the subjects that pushes an SME toward PLM.

Viewer

An application for viewing, measuring and annotating a model without a design license. The right tool for purchasing, production and subcontractors — and a license saving that's often overlooked.

Windchill

PTC's PLM, well established in series manufacturing and among tier suppliers, robust on changes and complex configurations. Demanding in configuration and governance.

Workflow

The route a document travels between its states, with the rights and notifications attached to each transition. Field advice: start with three states. Eight states and four approvers from day one, and nobody follows while everybody bypasses.

The confusions that cost the most

If you took only three distinctions from this glossary, take these — I find them misunderstood in almost every company I work with:

• Version and revision. One traces the work, the other commits the company toward production and the customer.
• eBOM and mBOM. Believing they're identical is the source of most gaps between engineering and the shop floor.
• Item and file. An item can exist without a file, and several files can describe one item. Conflating them makes any ERP integration painful.