# System functions and reference

> Function keys, screenshots, the symbols used in this manual, how a rule is written, what changed in V3.1, customization, and troubleshooting.

---

LLMS index: [llms.txt](/llms.txt)

---

This page collects the mappings and project details you look up rather than
learn in sequence.

## Function and system keys {#functional}

F1–F12 behave as standard function keys by default; hold Hyper to send their
media or system functions instead. The cyan block covers the whole top row plus
the screenshot keys.

| Key | Hyper action | + ⌘ |
| :--- | :--- | :--- |
| \` | Area screenshot to clipboard | Area screenshot to file |
| F1 / F2 | Brightness down / up | Desktop 1 / 2 |
| F3 | Mission Control | Desktop 3 |
| F4 | Spotlight | — |
| F5 / F6 | Keyboard light down / up | — |
| F7 / F8 / F9 | Previous / play-pause / next | — |
| F10 / F11 / F12 | Mute / volume down / volume up | — |
| F13 | Full screenshot to clipboard | Full screenshot to file |
| F14 | Screenshot menu | Legacy Touch Bar screenshot |
| F15 | Play / pause | — |
{.matrix .wide caption="Karabiner-Elements 15.1 and later follow System Settings › Keyboard › Keyboard Shortcuts… › Function Keys"}

The screenshot keys follow one convention: the plain Hyper chord puts the
capture on the **clipboard**, and adding ⌘ writes it to a **file** on the desktop.

| Chord | Emits | Result |
| :--- | :--- | :--- |
| ✱ + \` | ⌃ + ⇧ + ⌘ + 4 | Select an area → clipboard |
| ✱ + ⌘ + \` | ⇧ + ⌘ + 4 | Select an area → file |
| ✱ + F13 | ⌃ + ⇧ + ⌘ + 3 | Whole screen → clipboard |
| ✱ + ⌘ + F13 | ⇧ + ⌘ + 3 | Whole screen → file |
| ✱ + F14 | ⇧ + ⌘ + 5 | Screenshot and recording menu |
{.matrix .wide}

> [!NOTE]
> Enable the Desktop 1/2/3 shortcuts under **System Settings › Keyboard ›
> Keyboard Shortcuts… › Mission Control** before using
> ⌘ + F1–⌘ + F3; macOS ships them disabled. Touch
> Bar behaviour applies only to legacy Touch Bar Macs; see the [official troubleshooting note](https://karabiner-elements.pqrs.org/docs/help/troubleshooting/touch-bar-function-keys/).

The six-key navigation cluster on a full-size keyboard gives the same three
system controls in smaller steps, by emitting ⇧ + ⌥ together with
the media key, macOS's own quarter-step modifier.

| Cluster keys | Action |
| :--- | :--- |
| Insert / ⌦ | Fine brightness up / down |
| ↖ / ↘ | Fine keyboard-light up / down |
| Page Up / Page Down | Fine volume up / down |
{caption="Quarter steps instead of the full increments on F1–F12"}

## Symbols {#symbols}

| Glyph | Name | Glyph | Name |
| :--- | :--- | :--- | :--- |
| ⇪ | Caps Lock | ✱ | Hyper |
| ⎋ | Escape | ␣ | Space |
| ⌘ | Command | ⌥ | Option |
| ⌃ | Control | ⇧ | Shift |
| ↩ | Return | ⌤ | Keypad Enter |
| ⇥ ⇤ | Tab / Back-tab | ⇭ | Num Lock |
| ← ↓ ↑ → | Arrow keys | ↖ ↘ | Home / End |
| ⇞ ⇟ | Page Up / Page Down | ⌫ ⌦ | Delete / Forward Delete |
| ⏫ ⏬ | Faster / slower | 🖲️ | Mouse wheel |
| 🖱️L / 🖱️R / 🖱️M | Buttons 1 / 2 / 3 | 🖱️B / 🖱️F | Buttons 4 / 5, back and forward |
{.wide caption="The notation used across this manual and in the keyboard maps"}

The ✱ symbol is a heavy asterisk. The ordinary asterisk has ASCII
code 42, the answer to life, the universe, and everything.

## How a rule is written {#rule-anatomy}

Every mapping in the configuration has the same shape. Reading one makes the
whole file legible, and makes the [customization](#customize) section below far
less intimidating:

```yaml
- description: 'control + h = ctrl + left (prev desktop)'
  type: basic
  from:
    key_code: h
    modifiers:
      mandatory: [left_control, right_command, right_control, right_shift, right_option]
  to:
    - key_code: left_arrow
      modifiers: [left_control]
```

The four `right_*` modifiers in `mandatory` are Hyper itself; they appear in
every rule that Hyper drives. Whatever else sits beside them, `left_control`
here, selects the control plane. `to` is what the application actually
receives.

## What changed in V3.1 {#changes}

V2 used only a handful of planes. V3 introduced the four-bit plane model, which
is what let the layout grow to 282 mappings without becoming arbitrary. The
earlier configurations are listed under [Versions](/docs/karabiner/#versions).

V3.1 then intentionally changed several defaults that older users will notice:

- clipboards moved to 6–0, and 1–5 are no longer slots;
- C and ⌘ + C launch Codex and Claude;
- Spotlight and Alfred 5 replace Launchpad and Alfred 4;
- F13 and F14 provide screenshots instead of previous / next track;
- ⌘ + D performs **Define** rather than opening Dictionary.

## Customize the configuration {#customize}


- [Configurator](/docs/karabiner/configurator/) (no tools needed) — Browse all sixteen planes, inspect the real Karabiner output of any key, rename the applications behind the yellow keys, and export a ready-to-import JSON file.
- [Edit the YAML source](https://github.com/Vonng/Capslock/tree/main/mac_v3) (full control) — Fork the repository, edit the human-readable `mac_v3/capslock.yml`, and regenerate the JSON. Any rule the Karabiner schema allows is available here.


The YAML is the source of truth and the JSON is generated from it. Regenerating
takes one command and [yq v4](https://github.com/mikefarah/yq):

```shell
make -C mac_v3 compile
```

A good first customization is claiming one of the seven free planes. Copy any
rule, change the left modifier in `mandatory`, and you have a whole keyboard's
worth of space that nothing else uses: plane 5
(✱ + ⌘ + ⌃) and plane 7
(✱ + ⌘ + ⌥ + ⌃) are both completely empty.

Keep the YAML and the generated JSON synchronized: the import link and the
Karabiner gallery both publish the JSON.

## FAQ and troubleshooting {#faq}

**A chord does nothing at all.**

Check **Settings › Complex Modifications** first: the ten rules are enabled
individually, and a fresh import leaves nothing on. If the rule is enabled,
open Karabiner-EventViewer and press the chord. It shows exactly what reaches
the system, which distinguishes a missing rule from an application that
swallows the shortcut.

**Caps Lock sends Escape but nothing else works.**

That is the signature of enabling only the first rule. `CapsLock to Hyper`
provides tap-Escape and hold-Hyper; the other nine rules provide everything
that Hyper then does.

**Why can a chord trigger macOS diagnostics?**

[Issue #30](https://github.com/Vonng/Capslock/issues/30) documents that
⌘ + ⌥ + ⌃ + ⇧ + \. can trigger macOS diagnostics. Remap that
system shortcut if it conflicts with your chosen plane.

**Why is Linux not supported?**

Desktop environments differ substantially. The author primarily uses Linux
through a macOS terminal. Native support could be implemented with tools such
as `xmodmap`; contributions are welcome.

**Why does the repository contain older macOS versions?**

Legacy Karabiner used XML. Karabiner-Elements replaced it for macOS Sierra and
later, so the older configurations remain for historical systems. They are
listed under [Versions](/docs/karabiner/#versions).

**Is the design original?**

The first AutoHotkey version dates to 2013 and the first Mac version to 2015.
The current configuration is listed in the Karabiner-Elements [complex-modifications gallery](https://ke-complex-modifications.pqrs.org/#caps_lock_enhancement).

## Project {#project}

Capslock Enhancement is maintained by [Vonng](https://vonng.com/en/) and
distributed under the [Apache License 2.0](https://github.com/Vonng/Capslock/blob/main/LICENSE).
Source, releases, and issue tracking live on [GitHub](https://github.com/Vonng/Capslock).

---

Backlinks:

- [Install](/docs/karabiner/getting-started/)
- [Developer workflows](/docs/karabiner/workflows/)