syntax - Double Underscore in PHP?

Question

What does the double underscores in these lines of PHP code mean?

$WPLD_Trans['Yes']=__('Yes',$WPLD_Domain);
$WPLD_Trans['No']=__('No',$WPLD_Domain);

Answer 1

Looks like you're using Wordpress - wp-includes/l10n.php defines __ as a function that translates a string (similar to gettext and its alias, _ but with an optional parameter for explicitly specifying a domain).