(5746) "And nine Red Heifers were made and the tenth will be made by the King Moshiach may he speedily be revealed. Amen may it be so" (Rambam Hil Parah Adumah 3:end) The boundary of the connections of all the Heifers to each other according to Rambam's viewpoint. (and the difference to the wording of the Mishnah - Parah 3:5)
Explanation of Rambam's words: "May he speedily be revealed. Amen may it be so"