ZC v1.5.0, using the Developer's Tool Kit to look for where the split_pages_results function display_links is used, I noticed that there's a difference between the calling sequence between the top and bottom links (main_page is missing from the array for the bottom links):

Code:
//includes/templates/template_default/templates/tpl_modules_product_listing.php

Line #26 : <div id="productsListingListingTopLinks" class="navSplitPagesLinks forward"><?php echo TEXT_RESULT_PAGE . ' ' . $listing_split->display_links(MAX_DISPLAY_PAGE_LINKS, zen_get_all_get_params(array('page', 'info', 'x', 'y', 'main_page'))); ?></div>

Line #42 : <div id="productsListingListingBottomLinks" class="navSplitPagesLinks forward"><?php echo TEXT_RESULT_PAGE . ' ' . $listing_split->display_links(MAX_DISPLAY_PAGE_LINKS, zen_get_all_get_params(array('page', 'info', 'x', 'y'))); ?></div>
Which version is correct?