Dalek writing

From Tardis Wiki, the free Doctor Who reference

The Daleks had a form of writing.

Dalek writing on a screen on Skaro at Davros' trial. (DWM: Emperor of the Daleks!)

Overview

During the 22nd century invasion of Earth, the Daleks placed notices around London locations with uncertain meaning. (DW: The Dalek Invasion of Earth)

Dalek writing was displayed both on screens and in the vision of certain Dalek factions. (DW: Remembrance of the Daleks)

Post-Last Great Time War Dalek markings

All Daleks from a post-Last Great Time War era had markings below the eyepiece.

While the exact purpose of these marking is unknown, they may be a form of identification or rank insignia.