VERSION

Returns the current application version.

I actually prefer to detect the presence of certain features in order to make the extension cross-compatible, but if for some reason version detection is the only solution that you have, then this constant will always be available for use.

// Feature detection
if (!class_exists('Alert')) {
    exit('Missing alert extension.');
}

// Version comparison
if (!defined('VERSION') || version_compare(VERSION, '3.0.0', '<'))) {
    exit('This extension is not compatible with your core application version.');
}

D

Returns the directory separator.

ENGINE

Returns the engine folder path.

LOT

Returns the lot folder path.

N

Returns the line ending character of current operating system.

PATH

Returns the application root path without the trailing directory separator.

P

Returns a placeholder character.

S

Returns an empty space character.

TEST

Disables or enables test mode.

VERSION

Returns the current application version.