ISO/National Annex Sheet numbers in Revit

Updated: Feb 23, 2020

Recently, I reached out to my Twitter followers with a query; how do you achieve ISO19650/BS-NA compliant sheet numbering in Revit? I focused primarily on my UK followers, as they're already 2 feet in the door on this one. I thought this was worth sharing in more detail and hope it makes for an engaging read!

And so it begins...

For those still in the dark on ISO19650 and the UK National Annex, these standards have emerged on the back of the British/PAS standards, specifically BS/PAS1192. For many of us working outside the UK these standard lurk on the horizon ominously, threatening to suddenly become forced upon us should our governments suddenly decide that we're better off doing things in a consistent manner (up for debate).

As a BIM Manager working in Australia, I was always aware of what was happening with these standards, but never had the time nor the reasoning to implement such a framework in my day-to-day work. As a BIM Consultant, I now have a wider vantage of clients with different needs, so I've taken it upon myself to get on top of how this system can be achieved within Autodesk Revit (specifically for drawing/Revit sheet numbering).

So I reached out to twitter...

Dilemma 1 (in Revit)

The UK National Annex numbering convention looks a bit like this:

There's some additional fields relating to suitability and revision, but typically these are left

out of the file number on an EDMS (and applied as versioning metadata).

Revit immediately presents us with a very wicked problem (albeit a limitation of software vs. a fault of the ISO/NA). Try fitting all of this into a callout bubble, yuck!

This limitation is quite 'hard-programmed' into the way markers behave in Revit. Section marker text unfortunately always remains parallel to the page orientation, so we can't use a custom made square/boxed head to hold the extended number either (the pointer geometry always rotates however).

To make matters worse, view markers do not support embedding of reference sheet shared parameters, so we can't fragment the number into the callout in rows (there are some dirty workarounds, but let's not go there).

Simply put, the Revit sheet number must match the callout number.

Dilemma 2 (in Revit)

The first logical response is to make the role plus the 4 digit number into the sheet number, and use sheet shared parameters to build the overall drawing number in the title block. Unfortunately this doesn't typically accommodate a robust numbering system, especially for architects (who can often generate more than 1000 sheets on a single project, always needing room to grow in sub-series).

Another 'hard-programmed' limitation is that Revit does not support the existence of sheets with duplicate sheet numbers (even if other custom parameter data differs). When I say 'sheet number', I don't mean the overall title block number, but the actual parameter 'Sheet Number' which comes by default with every Revit Sheet.

The next train of thought usually involves realizing that some common sheet breakdown data already exists in the ISO/NA standard, specifically 'Level' and 'Volume'. With these in front of the 4 digit number, we essentially get up to 8 unique numbers to break down our drawings. This leaves us with 2 digits per sub-series, and 100 drawings per sub-series, per level, per zone; more than enough!

But they're so far away; there is a good 7 characters between them and our 4 digit number in the drawing number. That's where my Twitter response began to yield a reality; the drawing number and the Sheet number do not need to match (they just need to relate).

Twitterflies and hurricanes

The responses began simply enough, such insights as below kicked it off:

Kieren confirmed my suspicion that in reality, most UK firms have already accepted that the Revit sheet number would need to omit any superfluous drawing numbering data. We can only afford enough digits to make the Revit sheet number unique, and clearly relate-able to the drawing number itself.

Oh, and I got the standard wrong already... off to a good start! Kieren always has a nice realistic way of tackling queries on Twitter, highly worth a follow.

Don't break the rules, bend them

Further responses showed me that most were 'bending the rules' in order to deliver in a way that the software allowed. No major missteps, typically just exceeding the 4 digit number limit by wrapping other fields into it (essentially rearranging the overall drawing number).

I'd like to note that these people are very likely applying workarounds to comply with the printed drawing number name beyond this, I'm just making some assumptions here.

Is there even a 'best' standard?

David kicked off a 'sub-discussion', as he predicted the 'CI/SfB' reference would draw out some alternative opinions on sub-series breakdown. For those not aware, he is referring to the 'Construction Index/ Samarbetskommitten for Byggnadsfragor' system, established at the end of the 1950's for the construction industry. I'm sure some of us likely follow company systems derived from this unknowingly.

The backlash actually came from a relevant point to the whole discussion; why/should we be trying to follow a specific system anyway?

It's a loaded point; we could try to template our entire industry (or even Revit) to ISO/NA, only to have a client request an entirely different approach - legacy data systems sometimes aren't built to handle new ones. NRM (RICS 'New Rules of Measurement) provides some alternative means for classifying and numbering elements, including sheets/work packages. Maybe this will become an ISO as well?


Pierre has been one of my strongest connections in the UK when it comes to BIM standards and understanding the reality of what clients are accepting and expecting. 100% recommend following him on Linkedin/Twitter and checking out the work he does with the aechive in the UK.

We often have lengthy Whatsapp calls (when he wakes up, just before I go to bed!) about how my work can draw upon his findings and vice versa. I knew that when he joined the conversation we were onto something!

Storing all the metadata in a 'Fullname parameter' - genius! If we look at handling all our fields as bite sized parameters, then joining them together using a scripted workflow, we have the ability to take more liberty with our Revit Sheet number (after all, it's really just facilitating callout references in the end).

Pierre's point brought in another participant to the discussion, and I felt I finally came across the 'eureka moment' of what I was seeking:

I've got to hand it to Laurence on what he put together; he really thought of everything in his approach. He's developed a workflow by which sheet numbers can be generated, updated and temporarily adjusted to suit BIM360 publishing numbering requirements.

In it's 'resting' state, the sheet number is kept in the zone/level/number convention, which is manage-ably squeezed into a callout bubble. Add-ins provide a powerful way to have assurance that nothing is missed in the drawing number generation process.

As a final layer of icing on this cake, I came across a great plugin via Kieren called Property Wizard. Whilst it does cost USD$30 per year for a single user, it offers the ability to automatically keep parameters set by combination of other ones; essentially keeping a workflow like Laurence's dynamic and controlled.

Where to from here?

As I mentioned at the beginning of my twitter post, I'm doing this both for my understanding as well as the development of an industry template. Whilst I doubt I'll release the template with a system as complex as Laurence's, it will be possible to achieve an ISO19650/UK National Annex numbering standard in the template.

One of the major motivators of releasing this template will be to educate others, so I want to get it right! This could be a means by which graduates or even students can be exposed to the reality of our industry and BIM prior to entering it; they need our guidance.

I hope to release the template mid to late this year on the website; still many more facets to develop beyond just this 'fun' little dilemma.

I'd like to thank everyone who participated in the discussion, I'm fortunate to live in a digital age where such valuable advice is simply a 'tweet' away (and for free).

I hope this helps others tackling a similar problem, I'm sure there are many of us!

- Gavin Crump @BIM Guru

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