Slat

Slats (PROSE: Prisoner of the Daleks) studded the weapons platform of the casings of most Daleks. (TV: Genesis of the Daleks, The Chase)

Variants
Following the early Dalek War Machines which were externally powered by static electricity transmitted through the metal floors of the Dalek City, (TV: "The Escape") later silver Daleks initially overcame this weakness by adding dishes to their casing, at the back of the weapons platform, to receive power, (TV: The Dalek Invasion of Earth) although even these were ultimately replaced by vertical rectangular slats around the midsection which absorbed other sources of power. (TV: The Chase) From then on, the weapons platforms of most Daleks, with the exception of those of the New Dalek Paradigm, were studded by slats. (TV: Genesis of the Daleks, The Chase)

The grey Daleks, beginning with the first Mark III Travel Machines presented by Davros, had grey slats with black sense globes. (TV: Genesis of the Daleks) They were subordinate to gold Daleks who likewise had slats matching their wider casing. (TV: Day of the Daleks) Beyond them, Supreme Daleks of the Supreme Council had a golden dome, grating section frame, slats, and sense globes on an otherwise black casing. (TV: Planet of the Daleks)

Later grey Daleks, seen during the Dalek-Movellan War, had black slats as well as sense globes. However, grey-slatted Daleks remained during this time, and appeared to serve as leaders to the black-slatted Daleks. (TV: Destiny of the Daleks) They followed a black Supreme Dalek which had black slats, but white sense globes. (TV: Resurrection of the Daleks)

Following the re-emergence of Davros, the grey Daleks became known as Renegade Daleks. Though their casings were a lighter shade of grey, they remained with black slats and sense globes. They followed a black Supreme Dalek with white slats and sense globes. (TV: Remembrance of the Daleks)

The white Imperial Daleks loyal to Davros had golden slats and sense globes. (TV: Revelation of the Daleks) Uniquely, the Special Weapons Dalek had a weapons platform with no slats. (TV: Remembrance of the Daleks)

The bronze Daleks, of the Last Great Time War and beyond, had golden slats and sense globes. (TV: Dalek) Contemporary Black Daleks, such as Dalek Sec, had casings coloured completely black including slats and sense globes. (TV: Army of Ghosts) Dalek X, the Dalek Inquisitor General, was distinguished by his black casing with golden slats and sense globes. (PROSE: Prisoner of the Daleks)

Post-Time War Daleks that posed as British Army Ironsides had dark green slats and sense globes matching their disguised casings. These Ironsides were equipped with army utility belts housing useful battlefield accoutrements strapped to the weapons platform, obscuring their slats. (TV: Victory of the Daleks)

The larger Daleks of the New Dalek Paradigm had weapons platforms with no slats. (TV: Victory of the Daleks)

Behind the scenes
The Daleks seen in the theatrical film Daleks' Invasion Earth 2150 A.D. (held to be an invalid source by this Wiki) all had silver slats regardless of the colour of their wider casing.