By default, items in the buffers, definitions and find definitions views are sorted alphabetically according to their name. The options in the Sort panel of the Editor Preferences dialog let you change this.
Leaves items in these lists unsorted. For views which list definitions, choosing this option lists definitions in the order in which they appear in the source code.
Sort buffers according to their names. This is the default setting.
Sort buffers according to the buffer package.
Sorts items according to the type of each item. This sorts different types of definition, or different types of buffer, as appropriate.