Previously unissued stamp with gothic overprinted "Mexico". Issued due to shortage of stamps, used mainly in Mexico City. Printed on sheet watermarked paper for revenue documents. "R.P..S." stands for "Rente Papel Sellado" and appears on about half of the stamps in sheet.
Without district overprint.
Exist with district overprint (MI 41I / SN 44)
Variety: recto-verso printing (SN 44a)