Mari 4.5v2 docs:

Layered

Control	Type	What it does	Dialog	Notes
	toggle	Toggles the influence of channels connected to the shader without disconnecting them from the shader input.		Displacement is toggled off by default.
Inputs \|Vector	dropdown	The channel controlling the vector field and resulting vector data from paint on the shaded surface.		This data is used by the vector inspector.
Inputs\| Displacement	dropdown	The channel controlling the displacement map and dynamic tessellation to show a more advanced preview of displacement.		This component is disabled for Ptex channels.
	button	Adds a new channel for the shader component.	Add Channel Dialog
Displacement \| Displacement Bias	entry box, slider	How much the white or black values are pushed or pulled from the surface.		From 0 to 1; defaults to 0.500.
Displacement \| Displacement Scale	entry box, slider	How much displacement is applied to the shaded surface. Lower values equal smaller displacement; higher values equal larger and more obvious displacement.		From 0 to 1; defaults to 0.500.
Displacement \| Displacement Range	entry box	What the range of displacement is. This setting is multiplied by the Displacement Scale to give the displacement.
Displacement \| Max Tessellation	entry box, slider	How many texels the surface is tessellated to.		From 1 to 64; defaults to 10.
Displacement \| Perturb Normals	dropdown	Selecting yes changes the displacement so that displacement moves the surface but leaves the surface normals as they are.

Shader Layers Tab Fields

Control	Type	What it does	Dialog	Notes
	dropdown, switch	Filter bar function that gives the choices: Name, Type, Attribute, and Color Tag. Depending on which filter option you select, the filter bar shows one of the following: • - filter by the type of layers by clicking on the associated icons. • - filter by the attributes of layers by clicking on the associated icons. • - filter by the color tags of the selected color icon.		Both Type and Attribute provide icons that allow you to set the parameters for your filter. Quickly clear the entry box by pressing the icon.
	dropdown	Click to select from the blend mode options available for individual layers. To adjust the blend amount, enter the value into the entry box, or adjust the slider located to the right of the blend mode menu. • - adjusts the blend mode amount.		This list does not include the advanced blend mode options.
	button	Opens the Advanced Blending menu, which gives options for blend modes and components, as well as blend amount.
	button	Adds a new shader to the layer stack from a dropdown menu list of: • Unreal, • Principled BRDF, • VRayMtl, and • Choose Diffuse And Specular.	Create Shader Dialog when selecting Choose Diffuse and Specular.	The Choose Diffuse and Specular option allows you to create a custom shader. Refer to the Create Shader Dialog for more information.
	button	Adds a mask to the selected layer or, if none is selected, the top layer in the layer stack.		If a mask has already been added to a layer, you cannot add a second mask using this method. You must create a mask stack using the right-click menu.
	button	Adds a mask stack to the selected layer, or if none is selected, the top layer in the layer stack.		Clicking on the mask stack icon opens the mask stack palette.
	button	Removes the shader from the layer stack.		Default shaders cannot be removed from the Shaders palette.
	button	Assigns a color to the selected layers. To clear an already assigned color, click the icon and select the gray color in the center of the palette. This effectively removes the color and returns it to the default color state.