In August 2024 we refreshed the website content. We have not done this page yet: it is scheduled.
Deep dive
The previous page gave an overview of the concept of 'multiple systems'. It is the issue which causes the most confusion, so I will go in to more detail here.
Problem statement
If we find ourselves managing multiple systems, we have a problem which should be obvious.
![A diagram showing the smallest possible Johnny.Decimal system: just an area, a category, and an ID. The ID is 11.01. Nothing has a name. The two boxes are linked with a caption, asking 'to which system does 11.01 refer?'.](/img/_new/13.02.01-two-conflicting-systems-1008x180@2x.png)
This is ambiguous. If I refer to 11.01
, which system am I referring to?
In this situation we need to expand to the multiple systems notation.
Definition
System: any single collection of Johnny.Decimal numbers from
00-09
through90-99
.
A warning
Using multiple systems should be a last resort. They add complexity, which we seek to minimise. They are not an 'advanced feature' that you should aspire to use.
For many years I had a single system for my entire home life.
There is a lot of room in a single Johnny.Decimal system. You have a hundred categories to play with, each with a hundred IDs. That's ten thousand individual items.
If you plan it well, a single system can take you a long way.
I tell you this to save you time: only use multiple systems if you need to.
The solution
It should be obvious that we require a further level of identification to differentiate our systems.
The recommended solution is to add a system ID above your areas.
Definition
System ID: a unique system identifier.
![The diagram now shows 'P01 Personal' above the first system and 'D85 Johnny.Decimal' above the second. These are our new system IDs.](/img/_new/13.02.02-systems-showing-name-1008x252@2x.png)
What should we call our systems?
On the previous page I introduced the system ID. Review that page now if you haven't already.
The system ID format is letter-number-number. This gives us system codes in the following range:
-
Start:
A00
-
End:
Z99
We choose a short ID, give our system a title, and that becomes the complete system ID:
-
A00 My first system
-
M49 Some system in the middle
-
Z99 My last system
Make your system IDs meaningful
I've said that A00
is the 'first system' here just to get the point across. You should be more imaginative with your system identifiers as it will help you remember them.
The letter-number-number scheme gives us twenty-six groupings of one hundred. I suggest using the letter to represent a very broad part of your life.1
Some suggestions
Which you should adapt to the way your own brain works.
-
P
might be all of your personal systems.- But this is kinda boring: if your name is Jill, why not go with
J
?
- But this is kinda boring: if your name is Jill, why not go with
-
I have chosen
D
to represent my Johnny.Decimal systems. -
W
feels obvious for work, but if you're going to be at one company for a while perhaps use a letter that represents the company.
Play with the numbers
Here are all of the current systems in my life and the rationale behind their identifiers.
-
D01
: the Johnny.Decimal website-
Picked before I'd thought about this properly, hence the boring
01
. -
If I chose this today I might pick
D80
because 80 is the port that websites serve traffic on. π€
-
-
D85
: the Johnny.Decimal business-
Because
85
kinda looks likeBS
which kinda sounds like 'BuSiness'. -
This is dumb but it works! I remember it.
-
-
L43
: my previous job.-
Which I quit to focus on Johnny.Decimal!
-
Because the company name looked a bit like that combination of letters and numbers.
-
-
L77
: our Learn with Lucy Excel course.-
A personal system, and in my old scheme (now defunct) this was the fourth system.
-
(It's really good! You should learn Excel.)
-
-
P01
: my entire personal life for a decade.-
For a long time this was my only system.
-
As with
D01
, this becameP01
because I hadn't thought this through at the time.
-
Order is irrelevant here
You should not consider order when choosing system identifiers: that is, X02
need not come after X01
. Prefer numbers with meaning over a numerical sequence.
There is a caveat here which we will address on a future page: if you fit one of the patterns that requires many systems, it will likely be simpler to use identifiers in sequence.
What if I already have a project code at work?
Many of you will be using this scheme at work. In that case, you may already have a well-defined project code.
This might be a job code, the cost code for the project, or some internal code used in another system.
If you already have a code, you should consider using it as the Johnny.Decimal system identifier. Why invent another code if you already have one?
Remember, all of this is guidance. Do what works for you. The thing that works is likely to be the thing that introduces the least friction: especially at work where you need other people's buy-in.
The full Johnny.Decimal ID
Whereas previously our IDs were of the form 11.01
, which we refer to in the abstract as AC.ID
, they have now expanded and are in the range:
-
A00.00.00
-
...
-
M23.45.67
-
...
-
Z99.99.99
We refer to this as SYS.AC.ID
.
Do I have to use the full ID everywhere?
It depends.
Is your reference unambiguous without it? Then prefer the short version.
See implementation details below for more detail.
How many systems should I have?
It depends on your 'pattern', which we get to on the next page. But, as I have said above, you should prefer as few systems as possible.
This is why we are free to choose system identifiers that 'make sense' to our brains. We don't need to start at A01
because we have 2,600 identifiers to choose from.
If you ever come close to 'using up' your system identifiers then you've probably done it wrong.
Implementation details
So how do I actually do this in real life?
File system
Typically, I just use the system identifier to contain my system's area folders.
![MacOS Finder screenshot showing multiple systems. Each is now labelled with a system number and name.](/img/_new/13.02.03-finder-showing-multiple-systems-1042x240@2x.png)
I have tried and rejected using the system identifier in front of some or all of the subfolders within the system. I found no benefit to this approach.
My email folder structure mirrors this technique.
File names
Where I do find benefit is in using the full SYS.AC.ID
identifier in a file name.
![The macOS 'File > Open Recent' menu. It shows a bunch of filenames: some start with 'P01', some with 'D85'.](/img/_new/13.02.04-file-recent-dialog-889x482.png)
This might seem crazy, but it dramatically increases the usefulness of your 'recently opened files' list.
This list, usually a mess of unrelated document names, suddenly becomes organised according to your Johnny.Decimal system.
And now any file that you need to email has its identifier embedded. I've used this to find a five-year-old file in a matter of seconds.
I recommend at least trying this approach to see if it works for you.
Notes
You must use the full SYS.AC.ID
identifier in the title of your notes.
The power of your index system is its ability to instantly and unambiguously find any item.
With multiple systems, we will inevitably track multiple items with the number 11.01
. This leads to confusion and slows you down.
![Screenshot of Bear showing three notes who all have the ID 11.01. Bear's search highlights them all.](/img/_new/13.02-bear-11.01-three-results-571x370.png)
When we know what we want, we should be able to find it immediately.
![Screenshot of Bear showing note 'M55.11.01' which is now the only one that Bear finds when we search for its full number.](/img/_new/13.02-bear-m55.11.01-missile-571x370.png)
An exception
When you have a single system in its own domain, you should not need to use the multiple system notation in that domain.
Definition
Domain: a part of your life disconnected from all other parts. Separate domains share no information, technology, or tools.
![A diagram showing two 'domains'. The first, 'home', contains 2 systems. They're both labelled with a system identifier. The second domain, 'work', only contains one system. So it doesn't need the system identifier.](/img/_new/13.02.05-domains-home-work-1044x684@2x.png)
It may be the case that when you go to work, your job is totally disconnected from your home life. You don't use your personal notes app, file system, or email at work. Work is an isolated domain.
In this situation it is still the case that you will have overlapping numbers. 11.01
is likely to exist across your various systems.
But this isn't a problem because at work, when you refer to 11.01
it is always clear which one you are referring to. Accessing or editing 'the wrong one' isn't possible.
Just use AC.ID
if you can get away with it. It makes everything simpler.
Footnotes
-
To be clear, you may use any system identifier anywhere. Just because you use
L
for a work system does not preclude you from also using it for something personal.
But it might be neater to keep the letter-domain relationship, and it will certainly help your brain. β©