Dice acts using sex dice. Dice may have numbers that do not form a counting sequence starting at one. One variation on the standard die is known as the "average" die. These are six-sided dice with sides numbered codice_3, which have the same arithmetic mean as a standard die (3.5 for a single die, 7 for a pair of dice), but have a narrower range of possible values (2 through 5 for one, 4 through 10 for a pair). They are used in some table-top wargames, where a narrower range of numbers is required. Other numbered variations include Sicherman dice and
Add-on (Mozilla) made to install the add-on on a version outside of this range, it will install but will be disabled. The success of a formal compatibility check is no guarantee the add-on will work, however. It is even possible to override the compatibility check using various extensions. The add-ons manager periodically checks for updates for extensions installed from the Mozilla Add-ons website, although checks for updates can be manually initiated by the user. If the developer includes provisions to check elsewhere, the add-ons manager will do so. Firefox 57 ("Quantum") ceases support for extensions based on XUL or the Add-ons SDK,