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# init(_:)

Creates a new field key set from the specified comma-separated string of three-letter keys.

```
init?(_ s: String)
```

## Parameters

`s`

The key set string representation.

## Discussion

Apple Archive supports the following three-letter keys:

- `typ`: The entry type (always included).
- `pat`: The entry path (always included for filesystem objects).
- `lnk`: The link path (always included for symbolic links).
- `dev`: The device id (always included for block and character devices).
- `uid`: The user id.
- `gid`: The group id.
- `mod`: The access mode.
- `flg`: The BSD flags.
- `mtm`: The modification time.
- `btm`: The backup time.
- `ctm`: The creation time.
- `dat`: The file data.
- `siz`: The file data size.
- `cks`:  The file data digest (POSIX 1003.2-1992 32-bit CRC).
- `sh1`: The file data SHA-1 digest.
- `sh2`: The file data SHA-256 digest.
- `sh3`: The file data SHA-384 digest.
- `sh5`: The file data SHA-512 digest.
- `xat`: The extended attributes.
- `acl`: The access control list.
- `duz`: The entry disk usage.
- `idx`: The entry index in input archive.
- `idz`: The entry size in input archive.
- `yec`: The file data error correcting codes.
- `yaf`: The list of archive fields (metadata entry).

---

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