> For the complete documentation index, see [llms.txt](https://docs.urbit.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.urbit.org/urbit-os/kernel/khan/types.md).
# Khan Data Types
Khan only uses a handful of types, described below.
## `+avow`
Thread result mold builder
```hoon
|$ [a] (each a goof)
```
Khan returns this structure when the thread either successfully completes, or fails.
If the [`+each`](/hoon/stdlib/1c.md#each) is `%.y`, it succeeded and `.p` contains the result in either a `$cage` or a `$page`. If the thread was run internally it's a `$cage`, and if it was run externally it's a `$page`.
If the `+each` is `%.n`, the thread failed and `.p` contains a `$goof`, which is:
```hoon
+$ goof [mote=term =tang]
```
The `.mote` is an error code like `%foobar` and the `.tang` contains something like a stack trace.
#### Example
```
> `(avow:khan cage)`[%.y %noun !>('foo')]
[%.y p=[p=%noun q=[#t/@t q=7.303.014]]]
> `(avow:khan cage)`[%.n %foo-error 'blah' 'blah' ~]
[%.n p=[mote=%foo-error tang=~['blah' 'blah']]]
```
***
## `$bear`
Thread location
```hoon
$@(desk beak)
```
This is tells Khan where to look for a thread. It's either a `$desk` or a full `$beak`. Khan will look in the `/ted` directory of the specified location.
#### Example
```
> `bear:khan`%base
%base
> `bear:khan`[~sampel %base da+now]
[p=~sampel q=%base r=[%da p=~2022.11.6..08.33.22..9818]]
```
***
## `$cast`
External thread argument
```hoon
(pair mark page)
```
This is only used if you're running a thread via Khan's external interface. The `$mark` specifies the output mark, and a `$page` is a pair of input `$mark` and raw noun.
#### Example
```
> `cast:khan`[%noun %noun 123]
[p=%noun q=[p=%noun q=123]]
```
***
## `+fyrd`
Mold builder for a thread run request
```hoon
|$ [a] [=bear name=term args=a]
```
The fields are:
* [`.bear`](#bear): thread location.
* `.name`: thread name. Khan will look in `/ted` for this. If it's in a subdirectory like `/ted/foo/bar.hoon`, you'd say `%foo-bar`.
* `.args`: a `$cage` if it's an internal request, and a [`$cast`](#cast) if it's an external request.
#### Examples
```
> `(fyrd:khan cage)`[%base %mythread %noun !>(123)]
[bear=%base name=%mythread args=[p=%noun q=[#t/@ud q=123]]]
> `(fyrd:khan cast:khan)`[%base %mythread %noun %noun 123]
[bear=%base name=%mythread args=[p=%noun q=[p=%noun q=123]]]
```
***
---
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