The flavor text for the grenade launcher in Only War on page 182 specifically calls out:
These shots can be arced high into the air as suppressive fire at unseen targets as well as being used directly against foes.
The weapon itself doesn't have the "indirect" trait, so is this just flavor text that has no actual rules bearing? Or is the weapon allowed to be fired indirectly (as many real world grenade launchers are) so long as one follows the same rules for indirect weapons fire, i.e. a spotter or auspex is required and if missed you have some x value for shot deviation?
Or is there some "suppressing" trait that I am missing? There seems to be some vague meaning behind this.