Cody Burleson

Patterns for PKM: The Johnny Decimal System

Category: Information Capture & Organization

· Personal knowledge management

Remember that article where we talked about building a pattern language for Personal Knowledge Management (PKM)? Well, it’s time to dive into our first pattern! Today we’re looking at the Johnny Decimal System — a clever approach to bringing order to digital chaos. (If you’re just joining us and wondering what this pattern language thing is all about, catch up on the intro here.)

JOHNNY DECIMAL SYSTEM

Version 2, last modified: Feb 5, 2025

AI-generated art (Midjourney, prompted by the author)

People struggle to find their digital files and folders, leading to wasted time, duplicated work, and lost information. Traditional folder hierarchies become unwieldy and confusing beyond three levels deep, while completely flat organizations lose the benefits of structure entirely.

Without a clear organizational system, digital spaces become chaotic. People create folders haphazardly, name them inconsistently, and struggle to remember where they put things. This leads to:

  • Lost files and wasted time searching
  • Multiple copies of the same information
  • Inconsistent naming conventions
  • Difficulty sharing locations with others
  • Mental strain trying to remember locations
  • Fear of losing important information

The deepest problem is that our minds need both structure and flexibility. Pure hierarchy becomes too rigid and breaks down, while pure flatness provides no guidance. We need a system that matches how our minds work.

We have observed that:

  1. People can easily remember two-digit numbers
  2. Ten is a natural grouping size for categories
  3. Three levels of hierarchy is a cognitive sweet spot
  4. Numbers provide clear order and reference
  5. The mind needs both structure and flexibility

Therefore:

Create a numerical organization system that divides all information into 10 areas (10–90), with up to 10 categories in each area (11–99), and numbers individual items within categories (11.01–99.99). Always write the numbers first, followed by descriptive names.

For example:

10-19 Administration
  11 HR Documents
    11.01 Employee Handbook
    11.02 Org Chart
20-29 Finance
  21 Invoicing
    21.01 Invoice Template
    21.02 Client List
30-39 Projects
  31 Project Alpha
    31.01 Project Charter
    31.02 Timeline

This creates a system that is:

  • Limited to three levels deep
  • Easy to reference verbally (“eleven dot oh one”)
  • Quick to navigate visually
  • Flexible within clear boundaries
  • Consistent across all contexts

The system works because it mirrors how our minds naturally organize information. The two-digit area codes become familiar landmarks. The decimal notation creates clear boundaries. The numbers provide order while the descriptive names provide meaning.

Most importantly, this pattern helps establish a CONSISTENT LOCATION (another pattern) for every piece of information while maintaining FLEXIBLE BOUNDARIES (another pattern) between areas. It works together with FILE NAMING CONVENTIONS (another pattern) and supports both INDIVIDUAL ORGANIZATION (another pattern) and TEAM SHARING (another pattern).

The success of this pattern has been proven in both personal and professional contexts. Individuals and organizations that implement it report:

  • Reduced time searching for information
  • Clearer file locations and references
  • Improved team coordination through shared numbering
  • Better digital organization sustainability
  • Reduced cognitive overhead in file management
  • More consistent naming and structure
  • Easier onboarding of new team members

This pattern has been particularly successful in:

  • Personal file management
  • Team documentation systems
  • Project management tools
  • Research organizations
  • Digital asset management
  • Knowledge bases
  • Shared drives and workspaces

The pattern is strengthened when combined with:

References

Inspired by the Project: 4th Brain vision, Patterns for PKM is a community initiative. We don’t invent these patterns, we just help identify and collect them into a pattern language. As a valued member of our community, you’re invited to share patterns and opinions about how to improve upon those we’ve published. Want to stay in the loop?

💬 Contact me to share your thoughts and ideas

First published on Medium on .

← Cody Burleson