You cannot move any objects for language elements (variables, arrays, sets, semphores, and so on). Language elements cannot be moved because, although they are referenced in project methods and in object methods, they are not actually created until 4th Dimension is running. Similarly, commands are part of 4th Dimension itself and cannot be copied from one structure to another. The following is a list of objects that can be moved:

Formats/Filters
Database Methods
Forms
Groups
Lists
Menus
Menu Bars
Picture Library Graphics
Plug-ins
Project Methods
STR# Resources
Style Sheets
Tips
Tables