DefaultNewCellStyle is a notebook option which specifies the default style to use for new cells created in the notebook.
DifferentialD[x] displays as \[DifferentialD]x.
DisplayFunction is an option for graphics and sound functions that specifies a function to apply to graphics and sound objects before returning them.
FischerGroupFi22[] represents the sporadic simple Fischer group Fi_22.
FischerGroupFi23[] represents the sporadic simple Fischer group Fi_23.
JankoGroupJ3[] represents the sporadic simple Janko group J_3.
LibraryFunctionError[name, code] represents an error returned from a LibraryFunction.
MathieuGroupM22[] represents the sporadic simple Mathieu group M_22.
MathieuGroupM23[] represents the sporadic simple Mathieu group M_23.
PatternSequence[p_1, p_2, ...] is a pattern object which represents a sequence of arguments matching p_1, p_2, ....