Regarding "addIstreamConstructorToTable"
 

Dear users,
I am new to openfoam. I am reading the temporal scheme of the solver, however, I find the following in ddtScheme.H which bothers me:

ddtScheme<Type>::addIstreamConstructorToTable<SS<T ype>> \
add##SS##Type##IstreamConstructorToTable_; \
Info<<"test in ddtScheme.H "<<endl;

I am confused about "addIstreamConstructorToTable" because I cannot find the definition of this template (I have tried using grep and doxygen). It seems it is a member of ddtScheme template but I cannot locate it in the definition.
Does anyone know the meaning of this template? Where is its definition? Any help will be appreciated.