Beginning with the regular session of the General Assembly convening in 1990, all bills introduced in the regular session shall receive numbers with a prefix consisting of a two-digit number representing the last two digits of the year in which such regular session convenes. All bills introduced in any special session shall receive numbers with a prefix consisting of a two-digit number representing the last two digits of the year in which the special session convenes, plus the letter "S". If more than one special session is convened in any year, the prefix shall consist of a two-digit number representing the last two digits of the year in which the special session convenes, the letter "S", and the number of the special session, as in "90S2" for the second special session convened in 1990.