Mark I

Mark I or Mark 1 often refers to the first version of a weapon or military vehicle, and is sometimes used in a similar fashion in civilian product development. In some instances, the Arabic numeral '1' is substituted for the Roman numeral 'I'. 'Mark', meaning 'model' or 'variant', can itself be abbreviated 'Mk.' Mark I or Mark 1 often refers to the first version of a weapon or military vehicle, and is sometimes used in a similar fashion in civilian product development. In some instances, the Arabic numeral '1' is substituted for the Roman numeral 'I'. 'Mark', meaning 'model' or 'variant', can itself be abbreviated 'Mk.'