WordPress at a glance
filter is not described

the_content_more_link filter-hook . WP 2.8.0

Filters the Read More link text.

Usage

add_filter( 'the_content_more_link', 'filter_function_name_7857', 10, 2 );
function filter_function_name_7857( $more_link_element, $more_link_text ){
	// filter...

	return $more_link_element;
}
$more_link_element(string)
Read More link element.
$more_link_text(string)
Read More text.

Where the hook is called

get_the_content()
the_content_more_link
wp-includes/post-template.php 322
$output .= apply_filters( 'the_content_more_link', ' <a href="' . get_permalink() . "#more-{$post->ID}\" class=\"more-link\">$more_link_text</a>", $more_link_text );

Where the hook is used (in WP core)

Does not used.