# 6.14. Directive reference

Morloc Manual > Building CLIs | https://morloc-project.github.io/docs/clis/directive-reference.html | prev: https://morloc-project.github.io/docs/clis/interface-as-data.md | next: https://morloc-project.github.io/docs/apis/index.md

Every docstring directive that affects the generated interface, grouped by where it may be written. A directive written in the wrong place is not an error; it is kept as prose and the build warns, so check this table when one appears to do nothing.

**Table 6. On the module docstring — the --' lines directly above module**

| Directive | Effect |
| --- | --- |
| `@epilogue` | Open a block. Every following docstring line, until the docstring ends, is printed verbatim below the options from `-hh` up. Use it for an "Examples:" section. |

**Table 7. On a term’s signature preamble — the --' lines directly above name ::**

| Directive | Effect |
| --- | --- |
| `@name <name>` | Name the subcommand something other than the Morloc term. |
| `@with <flags>=<term>` | Attach an output action whose result stays typed. See [Output actions](https://morloc-project.github.io/docs/clis/output-actions.md). |
| `@render <flags>=<term>` | Attach an output action whose result is written as final bytes. |
| `@return <text>` | Describe the return value. The same as a docstring on the signature’s last type. |
| `@epilogue` | Open a block printed verbatim at the foot of this subcommand’s help, after its argument and return blocks. Use it for the command’s own "Examples:" section. The top-level help shows only the module’s block. |

**Table 8. On an argument — the --' lines directly above a type inside a signature**

| Directive | Effect |
| --- | --- |
| `@arg <flags>` | Make this argument an option rather than a positional. Requires `@default`. Not allowed on `Bool`. |
| `@default <json>` | The value used when an option is omitted, written as JSON. |
| `@true <flags>` | On a `Bool`: the flag that sets it true. The default becomes false. |
| `@false <flags>` | On a `Bool`: the flag that sets it false. The default becomes true. See the warning in [Arguments](https://morloc-project.github.io/docs/clis/arguments.md). |
| `@metavar <NAME>` | Name the argument. Becomes the placeholder in help for an option, and the property name in the machine-readable views. |
| `@many` | Accept several argv tokens and assemble them into a list. The argument type must be a list; as a positional it must be the last one. |
| `@stdin` | Make a `Str` positional optional and read standard input when it is omitted. See [Reading a stream from standard input](https://morloc-project.github.io/docs/clis/reading-stdin.md). |
| `@source inline` / `file` | Where the bytes come from. See [Input shape](https://morloc-project.github.io/docs/clis/input-shape.md). |
| `@form list` / `bytes` / `bytes-only` / `packet` | How the bytes are read. |
| `@check.path r` / `w` / `x` / `rw` | Require the argument to be a path satisfying the mode. |
| `@list.source`, `@list.form`, `@list.check.<kind>` | The same three, applied to each element of a `@form list` argument. |
| `@unroll` | On a record argument: split it into one flag per field. `@unroll false` opts one use out. |

**Table 9. On a type, record, or record field definition**

| Directive | Effect |
| --- | --- |
| `@metavar <NAME>` | On a `type` or a record in either form: the metavar inherited by every argument of that type. |
| `@mime <type/subtype>` | Attach a media type to a type. See [Output actions](https://morloc-project.github.io/docs/clis/output-actions.md). |
| `@arg`, `@default`, `@true`, `@false` | On a record field: the same meaning as on an argument, applied when the record is unrolled. |
| `@arg <flags>` | On a `record` definition: declare the group flag that accepts the whole record at once. |

**Table 10. Modifiers and value references, written inside another directive**

| Token | Meaning |
| --- | --- |
| `@default` | On a `@with` / `@render` directive: this action fires when no action flag and no `-f` is given. At most one per command. |
| `@stream` | On a `@with` / `@render` directive of a `@collect` command: apply the handler to each batch instead of the gathered stream. |
| `@offset` | As a handler argument under `@stream`: the number of elements already written. |
| `@value` | As a handler argument: the value being formatted. Appended last if not written explicitly. |
| `$1`, `$2`, …​ | As a handler argument: the command’s own Nth argument. |

One more directive is a deprecated spelling rather than a feature: `literal: true` means `@source inline`. It still works, and the build warns when you use it.