That's a good question. I tried a variety of options, but it stabilised on something that could be termed "micro-summary of context as file name". Example:

   - giraffes.html
   - giraffes_in_history.html
   - natural_predators_of_giraffes.html
   - grade_inflation.html
   - graffiti.html
   - genghis_khan.html       
   - grassroots_lobbying.html

Since all my Zettel are version controlled anyway, I don't see the point of tracking dates/times in filenames (or the file itself). I've now got so many Zettel that I can no longer recall even descriptive names like the above anyway: is the Zettel called giraffes_in_history.html or history_of_giraffes.html ...? So in practise, nowadays, when I look for related Zettel I always use grep with words I expect to be in the relevant Zettel. Example:

   grep -i giraffe *.html

It works really well.

What I do recommend is writing a little tool that produces filenames in a consistent way. (E.g. stripping out 'weird' characters, removing capitalisation etc.) I found that the more uniform filenames, file structure etc, the easier searching remains. Moreover, writing tools that mine / transform Zettel is also easier when the setup is uniform.

I also tried adding structures by subdirectories

   - computer_science
   - economics
   - biology

etc, but that didn't scale, since everything is connected to everything else. Knowledge is not tree- or DAG-structured. Flat file structure + hyperlinks works for me.

Did you try tags? If you have I'm interested in what you might have to say about them.

I liked Gmail originally because it used tabs. I have seldom had an email that was permanently tagged with more than one tag, but I have imagined having files in a filesystem with multiple tags. Bloggers commonly use tags but I don't know if they're successful.

On a filesystem where tags were not native, you could implement tags as subdirectories, using symlinks to achieve that the same file had multiple paths giraffes/history.html and history/giraffes.html.

   Did you try tags? 

No. I found that many of my early ideas on how to structure my notes didn't scale, made evolution of my system more difficult. So later I tried not to impose addition structure. Tagging enforces a structure, and how I classify ideas changes over time. What do tags give that grepping words doesn't?

Finally getting around to answering this:

I use a "Travel ideas" tag on emails from cruise lines if they suggest a specific place, time and cost to travel somewhere. Those words aren't in the email. The criteria that qualify the email for the tag are easy to check in a scan of the message but I don't know how I'd grep for them.

I still do searches but for other reasons.

If you wrote a note about a neutrino-hunting instrument at the South Pole, how many searches would it take you to find it later? What about a science station at McMurdo, which is in Antarctica but not at the South Pole?

You could allow yourself to have or not have a line of free association, whose only purpose was to match future searches that would otherwise miss because of how the content was phrased.

Thanks for the detailed answer. Very helpful tips.

Regarding timestamps: I have a Python script triggered by Alfred App on my Mac. The script creates markdown files based on a template. The template has a header section with helpful infos like `Created: yyyy-mm-dd`.

Here is my template (with filled out placeholders):

```

Created: Fri, 2019-10-11 12:27:18

Title: BOOK - METAPHYSICS - ARISTOTELES

Author: Ugur

FileID: fid-20191011-122718-440741

Base Header Level: 2

Tags: #ethics #philosohy

[%Title]

{{TOC}}

# WRITEHERE

```

This is a markdown template that can be rendered by `iA Writer`.

Thanks! That was really helpful to me in understanding how it works. That implementation shows the concept very well.