WordPress at a glance
filter is not described

excerpt_more filter-hook . WP 2.9.0

Filters the string in the "more" link displayed after a trimmed excerpt.

Usage

add_filter( 'excerpt_more', 'filter_function_name_7694' );
function filter_function_name_7694( $more_string ){
	// filter...

	return $more_string;
}
$more_string(string)
The string shown within the more link.

Where the hook is called

wp_trim_excerpt()
excerpt_more
wp-includes/formatting.php 3332
$excerpt_more = apply_filters( 'excerpt_more', ' ' . '[…]' );

Where the hook is used (in WP core)

wp-includes/default-filters.php 553
add_filter( 'excerpt_more', 'wp_embed_excerpt_more', 20 );