---
name: "nl_types.h"
section: "0p"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/nl_types.h"
---

# nl\_types.h(0p)

data types

## PROLOG

This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

## NAME

nl\_types.h — data types

## SYNOPSIS

```
#include <nl_types.h>
```

## DESCRIPTION

The *\<nl\_types.h\>* header shall define at least the following types:

- **nl\_catd**

  Used by the message catalog functions *catopen*(), *catgets*(), and *catclose*() to identify a catalog descriptor.

- **nl\_item**

  Used by *nl\_langinfo*() to identify items of *langinfo* data. Values of objects of type **nl\_item** are defined in *\<langinfo.h\>*.

The *\<nl\_types.h\>* header shall define at least the following symbolic constants:

- NL\_SETD

  Used by *gencat* when no $*set* directive is specified in a message text source file. This constant can be passed as the value of *set\_id* on subsequent calls to *catgets*() (that is, to retrieve messages from the default message set). The value of NL\_SETD is implementation-defined.

- NL\_CAT\_LOCALE

  Value that must be passed as the *oflag* argument to *catopen*() to ensure that message catalog selection depends on the *LC\_MESSAGES* locale category, rather than directly on the *LANG* environment variable.

The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.

```
int       catclose(nl_catd);
char     *catgets(nl_catd, int, int, const char *);
nl_catd   catopen(const char *, int);
```

*The following sections are informative.*

## APPLICATION USAGE

None.

## RATIONALE

None.

## FUTURE DIRECTIONS

None.

## SEE ALSO

***\<langinfo.h\>***

The System Interfaces volume of POSIX.1‐2017, *catclose()*, *catgets()*, *catopen()*, *nl\_langinfo()*

The Shell and Utilities volume of POSIX.1‐2017, *gencat*

## COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting\_bugs.html .