Hi Mashudu,
Can you explain what sort of transformer are you talking about? What is the taping no 1 that you have mentioned? is that the supply taping 110/230Vac etc of a battery eliminator or some product of that sort? or just a bare trafo?
are you referring to a multitap secondary of a transformer? if this is the case, the #1 position is usually the lowest voltage output but not all are configured this way.
as what bipin pointed out, are you referring to the primary multitap. if that is the case the #1 is the 110vac, #2 is the 220vac and #3 is the 440vac.