12. reservation of stock, etc. the company shall at all times reserve and keep available, solely for issuance and delivery upon exercise of the warrant, the number of shares of common stock (or other securities) from time to time issuable upon exercise of the warrant. all shares of common stock (or other securities) issuable upon exercise of the warrant shall be duly authorized and, when issued upon such exercise, shall be validly issued and, in the case of shares, fully paid and nonassessable with no liability on the part of the holders thereof, and, in the case of all securities, shall be free from all taxes, liens, security interests, encumbrances, preemptive rights and charges. the transfer agent for the common stock, which may be the company ('transfer agent'), and every subsequent transfer agent for any shares of the company's capital stock issuable upon the exercise of any of the purchase rights represented by this warrant, are hereby irrevocably authorized and directed at all times until the expiration date to reserve such number of authorized and unissued shares as shall be requisite for such purpose. the company shall keep copies of this warrant on file with the transfer agent for the common stock and with every subsequent transfer agent for any shares of the company's capital stock issuable upon the exercise of the rights of purchase represented by this warrant. the company shall supply such transfer agent with duly executed stock certificates for such purpose. all warrant certificates surrendered upon the exercise of the rights thereby evidenced shall be canceled, and each such canceled warrant shall constitute sufficient evidence of the number of shares of stock which have been issued upon the exercise of such warrant. subsequent to the expiration date, no shares of stock need be reserved in respect of any unexercised warrant.
13. registration and transfer of warrants, etc.
13.1. warrant register; ownership of warrant. each warrant issued by the company shall be numbered and shall be registered in a warrant register (the 'warrant register') as it is issued and transferred, which warrant register shall be maintained by the company at its principal office or, at the company's election and expense, by a warrant agent or the company's transfer agent. the company shall be entitled to treat the registered holder of any warrant on the warrant register as the owner in fact thereof for all purposes. if and when any warrant is properly assigned in blank, the company shall treat the bearer thereof as the owner of such warrant for all purposes. subject to section 10, a warrant, if properly assigned, may be exercised by a new holder without a new warrant first having been issued.