The [[Sign Language]] has diverged over the millennia, since the [[Space Marine Legion|Legions]]' were [[Founding|divided]] into [[Chapter]]s and each has adapted it for their own use.{{Fn|1}} Space Marine Legionaries of M30 also used [[Hortcode]], another sign language of the Imperium.{{Fn|2}}  The [[Sisters of Silence]] are fluent in various forms of sign language, but since the years of the [[Horus Heresy]] knowledge of the [[Legiones Astartes]] battle-signs has largely become redundant and atrophied . This is due to its the two organisations various changes over the millennia and lack of interaction, as well as contemporary Astartes battle-sign fracturing into numerous divergent forms in by M41.{{Fn|1}}