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filter is not described

comment_form_submit_button filter-hook . WP 4.2.0

Filters the submit button for the comment form to display.

Usage

add_filter( 'comment_form_submit_button', 'filter_function_name_5051', 10, 2 );
function filter_function_name_5051( $submit_button, $args ){
	// filter...

	return $submit_button;
}
$submit_button(string)
HTML markup for the submit button.
$args(array)
Arguments passed to comment_form().

Where the hook is called

comment_form()
wp-includes/comment-template.php 2446
$submit_button = apply_filters( 'comment_form_submit_button', $submit_button, $args );

Where the hook is used (in WP core)

Does not used.