- NexSysIT Editorial Team
- 23 Sep 2026
- 19 min read
The AEC IT Glossary: 60 Terms, Defined the Way a Practice Director Needs Them
Most IT glossaries define words. This one defines the words with the number, the rule or the vendor’s own statement attached, because a definition of worksharing that doesn’t say it fails over a VPN isn’t much use to the person deciding whether to open a second office. Every price is Autodesk’s Australian list price ex GST as at 23 September 2026, and every rule is the vendor’s or the standard’s, not ours.
It’s in six groups: Licensing and Autodesk · Revit and the model · Information management · Construction delivery · Infrastructure and storage · Security and recovery. If a tender clause or a renewal email uses a word that isn’t here, tell us and we’ll add it.
Licensing and Autodesk
Named-user subscription
Autodesk’s licensing model since the retirement of network licences. Each subscription is assigned to one person in the Autodesk account, who can install the software on up to three devices and run one instance at a time. It can’t be shared, and multi-user renewals ended on 7 February 2024.
Flex
Autodesk’s pay-per-day option for occasional users. Tokens are bought in packs, valid for a year, and a day of use draws a fixed number: 7 for AutoCAD, 9 for Civil 3D, 10 for Revit. When someone holds both a subscription and Flex, Autodesk uses the subscription first. Cheaper than a subscription below roughly two days a week.
AEC Collection
Autodesk’s bundle for architecture, engineering and construction. It includes Revit, AutoCAD, Civil 3D, Navisworks Manage, 3ds Max, InfraWorks, ReCap Pro and Autodesk Docs among nineteen products, all licensed to one named user. Worth it for anyone who opens two or more of the big three.
Revit LT
The cut-down Revit. It opens the same files but has no worksharing, no MEP or structural tools, no in-product rendering, no Dynamo and no point clouds. Right for the sole practitioner and the reviewer. Wrong for anyone in a shared central model.
AutoCAD LT
2D drafting without the 3D, the APIs or the seven industry toolsets. In a Revit practice, most AutoCAD seats should be LT, because the work is opening consultants’ DWGs rather than documenting in AutoCAD.
Autodesk audit
Autodesk’s formal licence compliance program. Any customer may be selected, and selection doesn’t mean suspicion. It starts with a letter or email, moves to a scan of the environment with Autodesk’s inventory tool, and ends with a licence compliance representative resolving what the scan found. A Perth engineering firm paid $65,000 in 2014 over unlicensed Autodesk products.
Perpetual licence
A licence bought once and owned, the way Autodesk software was sold before subscription. No longer available for new purchases. Old perpetual installs still running are unsupported and show up as a finding in an audit scan.
Elite Partner
Autodesk’s top partner tier for resellers, and NexSys is one, as well as Autodesk’s FY25 Customer Success APAC Partner of the Year. The list price is the same through a partner as direct; what differs is the audit, the deployment and the support that come with the invoice.
Revit and the model
BIM (building information modelling)
Designing and managing a building as a shared digital model rather than as separate drawings. The model holds geometry and data from every discipline, so architecture, structure and services can be coordinated, visualised and checked before anything is built, which reduces errors, risk and rework and improves quality across the construction industry. Each team contributes its own model, and those are combined into a federated model. AI tools are now arriving inside BIM software, Revit 2027’s Autodesk Assistant among them, and construction managers are using AI for scheduling, resourcing and site safety, but the data they work from is still the model.
Central model
The single Revit file that a workshared project team synchronises to. Each person works in a local copy and syncs changes back to central, which is why the two need to be on the same network or on a platform that serves the file rather than syncing it. The most valuable file on most practices’ networks, and the one backup tests should restore.
Worksharing
Revit’s mechanism for letting several people work in one model at once through a central file, worksets and local copies. It needs a file server on the local network, Revit Server, Autodesk’s cloud worksharing, or a platform built to serve the central model. It doesn’t work over a VPN. Autodesk says so.
Local copy
The per-user copy of a workshared Revit model that lives on the workstation and synchronises with the central model. Autodesk’s guidance is that the local copy and the central file belong in the same geographic location.
Worksets
The named subdivisions of a workshared Revit model that let people check out and edit parts of the building without treading on each other. Checked out is checked out. A worksets scheme that matches how the team actually works is half of a quiet central model.
Linked model
A Revit or CAD file referenced into another model rather than merged with it, usually the structural or services engineer’s model linked into the architect’s. Links need paths that resolve on every workstation, which is where sync-based cloud storage falls over.
External reference (xref)
AutoCAD’s equivalent of a linked model: a drawing referenced into another drawing by path. Autodesk documents that xrefs stored on SharePoint aren’t found unless the referenced files are downloaded locally, and that’s why a civil drawing with forty xrefs is unusable from a browser. Slow rather than broken, which is worse.
Federated model
A coordination model assembled from several disciplines’ models, usually in Navisworks, without merging them. Clash detection runs against it, and opening one is the job that makes the night before a submission slow.
Clash detection
Checking a federated model for places where two disciplines’ elements occupy the same space, a duct through a beam or a pipe through a column, so the conflict is resolved in the model rather than on site, before construction begins. Usually run in Navisworks or Autodesk’s cloud tools. Cheap to find in a model. Expensive to find with a crane on site.
IFC (Industry Foundation Classes)
The open data format for exchanging BIM models between different software, maintained by buildingSMART and published as ISO 16739. It’s how an Archicad architect and a Revit engineer share a model. Not lossless, so agree in the BEP what goes across in IFC and what stays native.
Point cloud
A laser or photogrammetry scan of an existing building or site, stored as millions of measured points and attached to a Revit or AutoCAD model. Point clouds are large, sit on the same storage as the model, and push memory and storage requirements past what a documentation seat needs. Size for the largest one you have.
Dynamo
Autodesk’s visual programming tool inside Revit, used for automating repetitive modelling and data tasks. Available in full Revit only, and one of the add-ins that application control policies need to allow for.
Revit Server
Autodesk’s on-premise product for worksharing across offices on a wide area network, with a central server and local accelerators. Largely replaced by cloud worksharing. Not available in Revit LT.
Cloud worksharing
Revit worksharing with the central model held in Autodesk’s cloud through Autodesk Construction Cloud and a BIM Collaborate Pro subscription. Works across offices without a VPN. It covers the Revit model. It doesn’t cover the rest of a project’s data.
Autodesk Construction Cloud (ACC)
Autodesk’s cloud platform for project delivery, including Autodesk Docs for document management, Autodesk Build, BIM Collaborate and the successor to BIM 360. Commonly run as a common data environment. Its recycle bin is not a backup, which is why SIINC exists.
Autodesk Docs
The document management layer of Autodesk Construction Cloud. It’s included with the AEC Collection and can’t be bought standalone, so a practice paying for a separate CDE subscription while its Collection seats include Docs is paying twice.
Workstation requirements
Autodesk’s Revit 2026 system requirements ask for the highest single-core clock speed available, 16 GB of memory for entry-level work and 64 GB or more for large models, and 100 GB of free disk for temporary files. Analysis packages and point clouds push those higher. Most everyday Revit work runs on a single core, which is why clock speed matters more than core count.
Information management
ISO 19650
The international standard for managing information over the life of a built asset using BIM, adopted in Australia as AS ISO 19650.1:2019 and 19650.2:2019. It defines who produces what information, when, in what state, and how it moves between parties. It arrives in a practice as a tender clause. Not a software choice.
Common data environment (CDE)
The agreed place where project information moves through the ISO 19650 states of work in progress, shared, published and archive, with gated transitions and an audit trail. A process as much as a platform. Autodesk Construction Cloud, Aconex, ProjectWise and 12d Synergy all run as one; a shared drive with an Issued folder doesn’t. The idea was popularised by the UK’s BIM Level 2 programme and PAS 1192, and its job is to be the single source of truth: one current, authoritative version of each piece of information that every stakeholder works from, instead of six emailed copies with (2) and FINAL in the file name. That avoids duplication and mistakes in the documentation. Better decision making on construction projects rests on it, and so does the ability to determine, months later, who knew what and when.
Work in progress, shared, published, archive
The four information states in ISO 19650. Work in progress is one team’s unchecked work, shared is checked and available for coordination, published is authorised by the client for use, and archive holds every superseded version, and Transport for NSW inserts a client shared state between shared and published.
Exchange information requirements (EIR)
The client’s statement of what information it wants delivered, when, in what format and at what level of detail. The document a practice is actually handed. Your answer to it is the BEP. PAS 1192, the British standard ISO 19650 replaced, called it the employer’s information requirements, and Australian tenders still use both names, sometimes interchangeably. Read either as the appointing party’s statement of what it wants and answer it the same way, with a BEP and a MIDP.
BIM execution plan (BEP)
The delivery team’s response to the EIR: how the information will be produced, by whom, with what tools and to what standard. A pre-appointment BEP goes in with the tender. A post-appointment BEP becomes the rulebook for the job. NATSPEC publishes a template.
Master information delivery plan (MIDP)
The schedule of every information container on a project, with who produces it and when. In practice, a spreadsheet. If you can produce a BEP and a MIDP that answer the EIR, you’re most of the way to ISO 19650 compliance.
Information container
ISO 19650’s word for a unit of information: a model, a drawing set, a schedule, a document. Named according to the standard’s container identification so a file name tells you project, originator, volume, level, type, role and number.
Appointing party, lead appointed party, appointed party
ISO 19650’s names for the client, the head consultant or contractor holding the information contract, and everyone else on the delivery team. Most practices are appointed parties. Know which you are.
Level of information need
ISO 19650’s replacement for level of detail and level of development: how much geometric, alphanumeric and documentary information a container needs at a given stage, defined by the purpose it serves rather than by a number. The standard also keeps the graphical model, the geometry you spin around on screen, apart from the information model, which is that geometry plus every schedule, report and data field attached to it, and while most project team members mean the Revit file when they say “the model”, ISO 19650 treats that file as one container among many, so its data storage and naming rules reach the spreadsheets too.
Change orders and proposed changes
Construction’s word for a formal variation to scope, cost or programme after the contract is signed. It’s the reason the archive state exists: pricing a proposed change means going back to the published set that was current when the price was agreed, and you can only do that if the superseded set was kept unaltered rather than overwritten by the next issue. Historical data pays for itself the first time a variation is disputed.
BIM implementation
What it takes to move a practice, or one project, onto ISO 19650 information management. Someone is named as information manager, naming and state protocols are adopted, a CDE is chosen, and every team that touches the project is trained to use it the same way. Done properly, it enhances collaboration and takes errors and cost overruns out of the job. Done as a software purchase, it changes nothing except the invoice.
NATSPEC National BIM Guide
The Australian reference guide for BIM projects, published by NATSPEC alongside BEP, Project BIM Brief and AIR, PIR and EIR templates that align with AS ISO 19650. The templates are the sensible starting point rather than a blank page. NATSPEC also publishes the national specification system, and a specification is the document that sets out materials, performance criteria, workmanship and quality standards for the work. Specifications sit beneath the National Construction Code, Australia’s mandatory building code for safety, health and amenity, and alongside voluntary rating tools such as Green Star here or LEED overseas, which rate a building’s environmental performance.
Construction delivery
AEC is three professions: architecture plans and designs buildings, engineering applies science to design the structures and systems inside them, and construction builds them to the design and the specification. Between them they make up most of the built environment. These are the delivery terms that turn up in the IT conversation.
Design and construct
A delivery method, called design-build overseas, in which one contract covers both design and construction, so the head contractor, the general contractor in American usage, employs or novates the design team and manages day-to-day activity on site with the trades. It matters to IT because a novated architect’s models move to a new owner partway through the project lifecycle, which runs from inception to handover, and the CDE and permissions have to move with them.
Defects list
The list of work to be corrected before practical completion and final payment, known as a punch list in the US. Usually produced as marked-up photos and PDFs on a tablet, and one of the reasons site teams need reliable access to the current drawings from the field.
Value engineering
A structured review of a design to keep its function while cutting cost, usually run when a tender comes in over budget. It generates a lot of model revisions in a short time, which is when version control and the archive state earn their keep.
Infrastructure and storage
Sync-based cloud storage
Services that copy a file to each machine and reconcile the copies afterwards: OneDrive, SharePoint, Dropbox, Google Drive. Ideal for documents, unsuitable for a Revit central model. Asked whether such services give an experience similar to worksharing on a local network, Autodesk’s knowledge base says the answer would be no.
Served storage
Storage presented to the workstation as a network location the application reads and writes directly, rather than a synced copy. What a file server, a NAS and a purpose-built cloud platform such as ALTO provide, and what worksharing needs.
NAS
Network-attached storage: the box in the comms cupboard that holds the project drive. Fast on a wired local network and paid for, and the right answer for a single-office practice with an offsite immutable backup. Stops being enough at the second office, the VPN or the ransomware.
VPN
A virtual private network: an encrypted tunnel from a remote machine into the office network. Fine for email and documents. Unsuitable for Revit worksharing, because the constant traffic between local and central was never designed for it. ALTO exists partly so practices stop needing one.
IOPS
Input/output operations per second, the measure of how many small reads and writes storage can serve. Revit models, federated coordination files and rendering assets generate a lot of them, which is why storage tiers chosen for modelling responsiveness matter more than raw capacity.
Virtual desktop
A Windows desktop that runs in a data centre and is streamed to the user’s screen. Used for Revit where the data and the compute need to sit together. Also where a practice would rather not put a workstation the price of a small car under every desk.
SD-WAN
Software-defined wide area networking, which routes traffic between offices over multiple internet links with policy rather than fixed circuits. What a multi-office practice runs instead of point-to-point links.
ALTO
NexSys’s purpose-built cloud architecture for AEC environments: project storage and compute in one place, sized for high-concurrency BIM modelling and large data transfer, with storage tiers, project-level segmentation, role-based access, an immutable backup isolated from primary workloads and 24/7 oversight. Replaces the NAS, the file server and the VPN. Free four-week trial, no contracts.
SIINC
NexSys’s SaaS platform for secure, automated backup of common data environments including Autodesk Forma, BIM 360, Aconex and ProjectWise. Exists because a CDE’s recycle bin is not a backup.
Security and recovery
Essential Eight
The Australian Cyber Security Centre’s eight mitigation strategies: application control, patch applications, configure Microsoft Office macro settings, user application hardening, restrict administrative privileges, patch operating systems, multi-factor authentication and regular backups. Eight controls, three jobs. The framework Tier 1 builders and state government clients now ask consultants to state their maturity against.
Maturity Level Two
The Essential Eight level built to stop a more capable adversary than an opportunist. The level most tender-driven AEC firms target. For backups it asks that unprivileged accounts can’t modify or delete them, that they’re retained securely and that restores are tested as part of disaster recovery exercises. That’s the control ransomware tests.
Immutable backup
A backup copy that cannot be altered or deleted for a set period by any credential, including a compromised administrator. The control that matters against ransomware, because attackers increasingly go after conventional backups first, and Synology’s own research puts backups as the first target in 94 per cent of attacks. The US Cybersecurity and Infrastructure Security Agency (CISA) recommends immutable backups for exactly that reason. They also protect against the less dramatic loss, the accidental deletion nobody notices for a month, and let a practice quickly recover to a known-good point.
Data loss and data protection
Data loss is the event: ransomware, a deletion, a corrupt file, a dead disk, anything after which the project can’t be brought back to the point the practice needs. Data protection is everything that decides whether it can be, meaning backup data held as an unaltered copy off the primary network, restores that have actually been run, and access controls on critical workloads so one stolen credential doesn’t reach all of it. In Australia the baseline is the Essential Eight’s backup control, and it’s the one most practices fail.
RPO and RTO
Recovery point objective is how much work you can afford to lose, in time; recovery time objective is how long you can afford to be down. ISO 22301 defines RTO as the period following an incident within which a product, service or activity must be resumed. Set per system, written into the agreement as numbers, and checked by a timed restore.
Restore test
Restoring a live project, not a sample folder, to an isolated environment and opening it in Revit or Civil 3D with someone watching, timed against the RTO. A backup that hasn’t been restored is a hypothesis.
Application control
The Essential Eight control that only lets approved software run. The one that collides with a Revit environment, because add-ins, Dynamo packages and render engines all need to be on the list first. Switch it on after, not before.
Multi-factor authentication
A second proof of identity beyond the password. Where the Essential Eight and Autodesk’s licensing model agree: every named-user subscription is already tied to a person’s sign-in, so MFA on that identity protects the licence and the model at once.
Data residency
Where data is physically held, including replicas and backups. The South Australian Cyber Security Framework’s supplier guideline asks providers to state it, and the 2024 Western Australian policy requires incident reporting within 24 hours. A question that now arrives with most tenders. Both frameworks treat a practice holding an agency’s data as a service provider with obligations of its own, and South Australia’s expects it to manage the security controls in its own environment rather than point at the agency’s.
Co-managed IT
A shared model where the practice’s internal IT person keeps day-to-day ownership and a provider takes defined areas, usually infrastructure, security tooling, disaster recovery and after-hours cover, with the boundary written into the agreement.
Systems audit
An end-to-end review of infrastructure and performance, cloud and hybrid, BIM and design workflows, security and compliance, and asset and lifecycle, delivered as a report with a priority against each finding and a cost to fix and not to fix. Finds the unassigned Autodesk seat and the untested backup before someone else does.
A caveat on all of the above. Definitions are the easy part. The hard part is knowing which of these apply to a practice of your size, and the answer for a five-person studio is “about a third of them”, so read the ones a tender or an invoice has actually put in front of you and leave the rest until they do.
- Written by
Written and reviewed by the NexSys engineers, design technology specialists and consultants who build and support IT for architecture, engineering and construction firms across Australia. Every price, rule and vendor statement is checked against its source on the date shown.
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