Aleph Tav

The Aleph is the first letter of the Hebrew alphabet. The Tav is the last letter. Hebrew is read from right to left. The Aleph Tav (אֵת) is found through out the Scriptures. Drawing the reader's attention to certain words in the Hebrew text. From the first verse of Genesis to the final verses of Revelation.

In the beginning (רֵאשִׁית rê'shı̂yth) Alohim created (בָּרָא bârâ') (אֵת) heaven (שָׁמַיִם shâmayim) and earth (אֶרֶץ' erets). Genesis 1:1

I am Alpha and Omega (Α Alpha; Aleph Ω Omega; Tav), Beginning (ἀρχή
archē) and End (τέλος telos),” says
aHaiah “who is and who was and who is to come, the Almighty.”  Revelation 1:8

I am Alpha and Omega (Α Alpha; Aleph Ω Omega; Tav), the first and the last:... Revelation 1:11

These things saith the first (πρῶτος prōtos) and the last (ἔσχατος
eschatos), which was dead, and is alive;
  Revelation 2:8

The Aleph Tav (אֵת) represents the eternal durability, strength, and security of the Creator's Covenant with His Bride (those born again), sustained through aHaishua's finished work, His seal, as the Kinsman Redeemer, shedding His blood as the redemptive price.

I am Alpha and Omega (Α Alpha; Aleph Ω Omega; Tav), the Beginning and the End, the First and the Last. Blessed are those doing His commandments, so that the authority shall be theirs to the tree of life, and to enter through the gates into the city. Revelation 22:13,14

Aleph  in paleo-hebrew symbolizes an Ox or strength.

Tav  in paleo-hebrew, looks like a cross, which could represent Messiah's finished sacrifice.

Also, we see in Ezekiel the mention of a mark.

And aHaiah said unto him, "Go through the midst of the city, through the midst of Jerusalem, and set a mark (tav)   upon the foreheads of the men that sigh and that cry for all the abominations that be done in the midst thereof. Ezekiel 9:44
and they shall look upon me (
) whom they have pierced,      Zechariah 12:9

A mark is also mentioned in Revelation. A different mark. The mark of the beast.