The expressions "patent pening" (sometimes abbreviated by "pat. pend." or "pat. pending") or "patent applied for" refer to a warning that inventors are entitled to use in reference to their product or process once a patent application has been filed, but prior to the patent being issued or the application abandoned. The marking serves to notify potential infringers who would copy the invention that they may be liable for damages (including back-dated royalties), seizure, and injunction once a patent is issued.