@@@. is the prefix for the global control variables and global functions.
@@@.quiet : 1 ---> quiet mode, 0 ---> not. cf. sm1 -q
@@@.esymbol : (e_) is the standard value. It is used to express
vectors internally. cf. fromVectors, toVectors
@@@.Dsymbol : (D) is the standard value for differential operator.
@@@.diffEsymbol : (E) is the standard value for difference operator.
@@@.Qsymbol : (Q) is the standard value for q-difference operator.