FronterVille firm Zynga is seeking a patent on virtual currency, it has been revealed.
UPSTO application 20100227675, 'Virtual Playing Chips in a Multiuser Online Game Network,' covers a server receiving a purchase request for virtual currency by a player.
The application stipulates that the credits are "non-redeemable" - they must only be used within a game, and cannot be sold outside of it.
The filing was made in March this year, with Zynga boss Mark Pincus one of the named "inventors."
It is unclear as yet whether the intention behind the patent, which has not yet been granted, is to corner the virtual currency market, or to help fend off the many third-party resellers of virtual goods and cash for Zynga games.
In April, Zynga sued virtual goods reseller Playerauctions.com, a site which sold Mafia Wars in-game items for real-world prices as high as $492,000, claiming copyright and trademark infringement.
Despite this USPTO application, Zynga recently signed an agreement to use Facebook Credits, from which the social network takes a 30 per cent cut, for the next five years.
The filing also seeks to lay claim to gifting in-game currency or objects to another player via a social network.
In addition, the application encompasses virtual chips for gambling games - this patent being granted may help successful Facebook title Zynga Poker bypass US gambling restrictions.
The full USPTO filing may be read here.