A dynamically configurable list management system that supports list
elements of multiple content types is presented. Each list element is
associated with an element type via an element type identifier. The
element type identifier uniquely identifies the element type to the list
management system. Each property associated with each element type is
included in the list. Each property is identified by a unique property
identifier. When adding a list element of a new element type to an
existing list that does not include any elements of the new element type,
the list management system identifies every property associated with the
new element type. For each property associated with the new element type,
the list management system determines which properties are not already
included in the list, and adds those properties that are not already
including to the list.