-- Syntax
concat mddExp with mddExp ... with mddExp along integer

-- Concatenating two images along the first dimension
SELECT CONCAT mr WITH mr ALONG 0 FROM mr

-- Arangement of 2 x 2 mr images
SELECT CONCAT (CONCAT mr WITH mr ALONG 0)
       WITH   (CONCAT mr WITH mr ALONG 0)
       ALONG 1
FROM mr