Thanks to my friend Jens Oetling in Germany for making this possible.
Recently my philatelist friend from Germany send me 2 Maxcard with 1969 Mahatma Gandhi stamp on Hannover Messe card with special cancellation of "Hannover Messegelände " means Hannover Fairground issued on 25-4-70.
Looks like this Maxcard and Special Cancellation was issued to celebrate opening of Hannover fair in 1970. The Hanover fairground is an exhibition area in the Mittelfeld district of Hanover, Germany. Featuring 496,000 m² of covered indoor space, 58,000 m² of open-air space, 27 halls and pavilions and a convention centre with 35 function rooms, it is the largest exhibition ground in the world.
In 1970 Hall 1 was opened, then the largest exhibition hall in the world. It becomes permanent home to CeBIT, a subdivision of the Hanover Industry Fair.