WordPress at a glance
function is not described

sanitize_bookmark_field() WP 2.3.0

Sanitizes a bookmark field.

Sanitizes the bookmark fields based on what the field name is. If the field has a strict value set, then it will be tested for that, else a more generic filtering is applied. After the more strict filter is applied, if the $context is 'raw' then the value is immediately return.

Hooks exist for the more generic cases. With the 'edit' context, the 'edit_(field)' filter will be called and passed the $value and $bookmark_id respectively.

With the 'db' context, the 'pre_(field)' filter is called and passed the value. The 'display' context is the final context and has the $field has the filter name and is passed the $value, $bookmark_id, and $context, respectively.

Hooks in function
Return

Mixed. The filtered value.

Usage

sanitize_bookmark_field( $field, $value, $bookmark_id, $context );
$field(string) (required)
The bookmark field.
$value(mixed) (required)
The bookmark field value.
$bookmark_id(int) (required)
Bookmark ID.
$context(string) (required)
How to filter the field value. Accepts 'raw', 'edit', 'attribute', 'js', 'db', or 'display'

Code of sanitize bookmark field: wp-includes/bookmark.php VER 5.0.3

<?php
function sanitize_bookmark_field( $field, $value, $bookmark_id, $context ) {
	switch ( $field ) {
	case 'link_id' : // ints
	case 'link_rating' :
		$value = (int) $value;
		break;
	case 'link_category' : // array( ints )
		$value = array_map('absint', (array) $value);
		// We return here so that the categories aren't filtered.
		// The 'link_category' filter is for the name of a link category, not an array of a link's link categories
		return $value;

	case 'link_visible' : // bool stored as Y|N
		$value = preg_replace('/[^YNyn]/', '', $value);
		break;
	case 'link_target' : // "enum"
		$targets = array('_top', '_blank');
		if ( ! in_array($value, $targets) )
			$value = '';
		break;
	}

	if ( 'raw' == $context )
		return $value;

	if ( 'edit' == $context ) {
		/** This filter is documented in wp-includes/post.php */
		$value = apply_filters( "edit_{$field}", $value, $bookmark_id );

		if ( 'link_notes' == $field ) {
			$value = esc_html( $value ); // textarea_escaped
		} else {
			$value = esc_attr($value);
		}
	} elseif ( 'db' == $context ) {
		/** This filter is documented in wp-includes/post.php */
		$value = apply_filters( "pre_{$field}", $value );
	} else {
		/** This filter is documented in wp-includes/post.php */
		$value = apply_filters( "{$field}", $value, $bookmark_id, $context );

		if ( 'attribute' == $context ) {
			$value = esc_attr( $value );
		} elseif ( 'js' == $context ) {
			$value = esc_js( $value );
		}
	}

	return $value;
}