Independent Models with the Independent special rule function with a greater degree of autonomy. All models with this special rule and the same name within a Detachment form an "Independent Unit". A Detachment can have multiple Independent Units within it, with each Independent Unit consisting of models of the same name. The remaining models (i.e., those without the Independent special rule) are referred to as the "Detachment Core".
All models within an Independent Unit must maintain a 2" Detachment Coherency with other models in the same Independent Unit and a Detachment Coherency of 6" with the Detachment Core - at least one model from each Independent Unit must remain within 6" of one or more models from the Detachment Core.
If the controlling player wishes, each Independent Unit may be issued its own Order during the Order phase - this can be a different Order from the rest of its Detachment. In addition, models within the Independent Unit may choose a different target than the rest of their Detachment when firing - all models within an Independent Unit must fire at the same target unless specified otherwise.
Though it has its own Order, the Independent Unit is still part of the larger Detachment, and thus activates and reveals its Order at the same time, is issued with a Fall Back Order if the Detachment is, etc. If the Detachment calls an Overwatch, an Independent Unit only discards its Advance Order or First Fire Order if one of its models fired during the Overwatch, not if other models from the Detachment did so.
A Detachment that contains one or more Independent Units is only considered to be Engaged if a model without the Independent special rule is Engaged. If one or more models with the Independent special rule are Engaged, then all models within that Independent Unit are also Engaged, however the larger Detachment can still act as normal, providing they maintain Detachment Coherency. In other words, an Independent Unit and its Detachment count as two separate Detachments for the purposes of determining Combats and determining which models are Engaged.
Models with the Independent and Deep Strike special rules may start the game in Reserve even if the larger Detachment is deployed on the battlefield - all models in an Independent Unit must be deployed in Reserve if one is. When the Independent Unit arrives via Deep Strike, it must be deployed within 6" of one or more models from the larger Detachment (i.e., within Detachment Coherency). The Independent Unit does not scatter, but must follow all other rules related to Deep Striking. If all other models from the Detachment have been destroyed before the Independent Unit has Deep Striked, then it is placed as if it were a normal Deep Striking Detachment.
Jump Packs Models with the Jump Packs special rule can move over all other models and areas of terrain, suffering no movement penalties for doing so, such as due to Difficult terrain or moving over an Obstacle. Models with the Jump Packs special rule cannot end their movement overlapping other models, nor can they end their movement within an enemy model's Engagement Zone unless they are issued with a Charge Order. They can move over Impassable terrain but cannot end their movement overlapping it - any model that ends their movement overlapping an area of Impassable terrain is destroyed.
Infantry models with the Jump Packs special rule can only end their movement on top of a Structure if they intend to Garrison it - if the Detachment does not Garrison the Structure, then any models overlapping with the Structure are destroyed.
A model with the Jump Packs special rule adds 1 to the result of all Fight rolls it makes against models Garrisoned within a Structure while issued with a Charge Order, in addition to any other modifiers.
Models with the Jump Packs special rule count as having the Bulky special rule for the purposes of Embarking on Transports. In addition, they can Disembark from a Transport with the Flyer special rule even if it does not have the Hover special rule, and a Transport with the Hover special rule does not have to Hover for them to do so.
