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filter is not described

get_the_terms filter-hook . WP 3.1.0

Filters the list of terms attached to the given post.

Usage

add_filter( 'get_the_terms', 'filter_function_name_825', 10, 3 );
function filter_function_name_825( $terms, $post_id, $taxonomy ){
	// filter...

	return $terms;
}
$terms(array/WP_Error)
List of attached terms, or WP_Error on failure.
$post_id(int)
Post ID.
$taxonomy(string)
Name of the taxonomy.

Where the hook is called

get_the_terms()
get_the_terms
wp-includes/category-template.php 1209
$terms = apply_filters( 'get_the_terms', $terms, $post->ID, $taxonomy );

Where the hook is used (in WP core)

wp-includes/revision.php 533
add_filter( 'get_the_terms', '_wp_preview_terms_filter', 10, 3 );