In which case is a shot considered Speculative?
When a Template weapon (Warning: we are meaning a Template weapon, not a Direct Template weapon) is shot against a model, which is the target of that shot, and the center of the Template is not placed over the targeted figure, then a Speculative Shot is performed and the BS-6 Modifier must be applied.
In other words, if the (For example) grenade is not going to fall over the targeted figure, but behind it or just besides it, in a point of the battlefield (but, of course, affecting the figure with the Template), then it is considered a Speculative Shot.
In this situation, in which the grenade doesn't fall over the target, the Speculative Shot Modifier, BS-6, is always applied, doesn't matter if there is LOF with the target or not: Even having LOF, not placing the center of the Template over the targeted miniature means the shot is considered Speculative.
This maneuver is very useful, for example, to face a figure with TO Camouflage behind a Partial Cover: just placing the center of the Template in a point of the game table where the Template affects the figure avoiding the Cover, we must apply only the BS-6 Modifier by Speculative Shot, and the Distance Modifier too, while with a normal shot we must apply the BS-6 Modifier by TO Camouflage, the Distance Modifier and also the Cover Modifier, we avoid with the Speculative Shot.
http://infinitythegame.wikispot.org/Speculative_Shot