For some types of updates it is necessary to update the datatype of a variable. When a new field is added, there isn't any reserved room in the data structure to host the field. DynAMOS uses shadow variables in support of such datatype updates. On variable creation a new shadow variable is created. The memory address of the variable is used to map into it's shadow using a hash table. When the new datatype is freed, it's shadow is also freed. A benefit of this technique is that only the functions that must use the new field need to be updated, instead of all functions that use the old datatype.