wp-includes/link-template.php:2704Displays the previous posts page link.
$labelstringoptionalnullfunction previous_posts_link( $label = null ) { echo get_previous_posts_link( $label );}Introduced in 0.71. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/link-template.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.