More terms need to be defined

• outline tasks (aka function tasks)
• successor (task)
• predecessor (task)
• parent (task)
• child (task)
• ascendant (task)
• descendant (tasks)
• lexical extension
• dynamic extension
• dependence
• expresion
• thread
• device
• directive
• sliced WD
• slicer policy
• data environment
• <others...>