(k)the manner in which any document relating to a Government security or any endorsement or a promissory note issued by [the Government] [Substitued for the words the Central Government by the Public Debt (Central) Government Amendment Act, 1949 (6 of 1949), Section 6 (1-4-1949)] may, on the demand of a person who from any cause is unable to write, be executed on his behalf;