i1 : X = new WrapperType of BasicList o1 = X o1 : WrapperType |

i2 : X {a,b,c} o2 = X{a, b, c} o2 : X |

i3 : X a o3 = X{a} o3 : X |

- HeaderType -- a class of lists with abbreviated constructors
- SelfInitializingType -- the class of all self initializing types

- WrapperType List
- WrapperType Sequence
- WrapperType Thing

- Describe -- the class of the output of describe
- Holder -- the class of all holder expressions
- Minus -- the class of all minus expressions
- NonAssociativeProduct -- the class of all nonassociative product expressions
- Parenthesize
- Product -- the class of all product expressions
- SheafExpression -- the class of sheaf expressions
- Sum -- the class of all sum expressions

The object WrapperType is a type, with ancestor classes Type < MutableHashTable < HashTable < Thing.