# tmux_option:key/0

- **Package:** libtmux_erlang
- **Language:** Erlang
- **Kind:** typealias
- **Source:** https://github.com/libtmux/libtmux-erlang/blob/d1b6308440cf9eb8f6647e7ae434bce60e849368/apps/libtmux_erlang/src/tmux_option.erl#L44
- **Page:** https://libtmux.org/en/erlang/latest/reference/t-tmux_option-key-0/

```
-type key() :: binary() | {binary(), non_neg_integer()}.
```

Canonical binary name; arrays use a structured non-negative index, never bracket syntax.