---
title: accept.language_filter_basic
summary: null
url: >-
  https://www.fastly.com/documentation/reference/vcl/functions/content-negotiation/accept-language-filter-basic
---

```
STRING accept.language_filter_basic(STRING requested_languages, STRING default, STRING accept_header, INTEGER nmatches)
```

**Available in:** all subroutines

Similar to `accept.language_lookup()`,
this function selects the best matches from a string in the format of an
`Accept-Language` header's value in the listed languages using the algorithm
described in [RFC 4647](https://tools.ietf.org/html/rfc4647), Section 3.3.1.

This function takes the following parameters:

1. a colon-separated list of languages available for the resource,
2. a fallback return value,
3. a string representing an `Accept-Language` header's value,
4. the maximum number of matching languages to return.

The matches are comma-separated.

## Example

```vcl
set bereq.http.Accept-Language =
  accept.language_filter_basic("en:de:fr:nl", "nl",
    req.http.Accept-Language, 2);
```