Data fragments are used for getting some units ( mainly including advanced/ elite units). Data fragments can be earned from Crates and the Data  Fragment shop ( and of which you need HQ Lv 6). Some data fragments can be used in the ​​​​​​ Armory ​​​​ ( Which you have to be at least Lv 6 to build an armory) Data fragments are also used in bracing for buildings( for instance, the HQ) and additional units