There are total 18 groups of segregation listed in IMDG Code section 3.1.4.4 starting with Group 1 Acid till Group 18 Alkali.
In case if a shipper decides to assign a substance, mixture, solutions or preparation under an N.O.S. entry, which is not listed in segregation groups as mentioned in the paragraph above, to a particular segregation group then she or he shall include this information in dangerous goods declaration.
This shall be done with the appropriate segregation group name preceded by the phrase “IMDG Code segregation group”
Example:
UN 1760 CORROSIVE LIQUID, N.O.S. (Phosphoric acid, acetic acid) 8 III IMDG Code segregation group – 1 Acids
IMDG Code Compliance Centre 