1.Guru Gobind Singh Ji Maharaj Himself ordered the writing of Dasam Granth Sahib Bir in 1698. He Himself wrote some pages and also did Signature in the end. This Bir is present at Takht Patna Sahib.
2. A copy was made of this Bir in the same year(
so we have 2 Dasam Granth Birs from 1698) and thats the Bir you are seeing in the pic.
3. Bhai Mani Singh jee did Parkash of this Mahaan Bir at Akal Takht Sahib and this bir was called Akaal Takht Sarup Bir.
4. Name of this Bir is also significant. A Bir of Dasam Granth was also prepared in 1696 by Dasmesh Pita Himself at Anandpur Sahib immediately after completing Charitropakyan. In the 18 Century when Khalsa was HIGHLY charrdikala, this bir was known as 'Anandpuri Bir' as the Panth at that time knew that this Bir was written/prepared in Anandpur Sahib.
Same way this bir was given the name "Akaal Takht Sarup Bir' as the Panth knew that this Bir was Parkash-ed at Akaal Takht Sahib by Bhai Mani Singh Ji himself.
5. In 1920's SGPC tast force hit this Bir Sahib with a Spear and threw it out of the window of Sri Akaal Takht Sahib. You can see the damage done by spear in the picture.
ਸਤਿਗੁਰਬਚਨਕਮਾਵਣੇਸਚਾਏਹੁਵੀਚਾਰੁ॥