The General tab contains Auxillary, Cryptomatte, and Render Layers AOV categories that separate render data such Cryptomatte generation, irradiance information, light direction, render noise, etc. The Cryptomatte AOVs work with the Direct Light, Path Tracing, and  Photon Tracing kernels to render Cryptomattes for use in compositing. They are rendered one at a time, and they contain the masks for all object layers or materials in a scene. The masks also have correct anti-aliasing, and they take into account other features such as motion blur, transparency, and depth-of-field.

Auxilliary AOVs

Irradiance - Any surface which contributes to the lighting or reflected lighting of the scene will be included in this AOV.

Light Direction - Outputs lighting direction information for the scene.

Noise - Outputs a noise map of the scene.

PostFX Media - Outputs the post process volume effects from the Imager object.

Camera Mask - Contains the average throughput for camera rays. For areas in the image where a camera does not create valid rays, this will be black. With many cameras the rest of this pass will be 100% white. Some cameras may set custom through puts due to vignetting or other effects. The Universal–Fisheye and Realistic lens cameras create vignettes within the camera, these vignettes will be visible in this render pass.

Alpha AOV - Outputs a greyscale image representing the areas that are transparent.

Post Processing - Outputs the post processing pass from the Imager object.

Shadow - The shadow AOV contains all direct light shadows that are calculated on the first path bounce. The AOV includes sun light provided by the Octane Daylight Environment. The Shadow pass excludes the Texture Environment if the texture environment does not consist of an image.

Cryptomatte AOVs

Material Node Name - The Material Node Name channel is used to create IDs by assigned materials in the scene. Using the same material on different objects will result in those objects having the same color (ID channel) in the cryptomatte output.

Material Pin Name - The channel ID is used to get polygon/material selections in the scene. Selections will be one channel, and null selections (nothing selected) will be in another channel.

Object Node Name - The Object Node Name channel is used to create ID Channels based on object names for each object in the scene.

Object Pin Name - The ID channel is based upon the names of the exiting Object pins in the scene. It is quite common to see most objects placed into the same ID channel, as Object Node Pin Names change, rarely, depending upon the object source.

Object Pin Name - The Cryptomatte channel is based on the names of the existing Object pins in the scene. 

Geometry Node Name - The ID channels are generated based upon the name of the scene geometry.

Render Layer - The ID channels are generated based upon the Render Layer ID in the Octane Layer node connected to objects in the scene. 

User Instance ID - The ID channels are generated as determined by the Instance IDs specified by the user.

Material Node - The Cryptomatte channel is based on distinct material nodes.

Object Node - The Cryptomatte channel is based on distinct Object nodes.

Instance - The ID channel is based on instance IDs.

Render Layers AOVS

Render layers are used to isolate objects as a separate primary render. More information can be found in the Render Layers section.  Render Layer AOVs further break down the render layers into any of three AOV component types.

Black Layer Shadows - Layer Shadows will output shadows of objects with a layer ID greater than 1. This option requires that the Alpha channel be enabled, otherwise the result will not be visible.

Layer Reflections - Layer Shadows will output shadows of objects with a layer ID greater than 1.

Layer Shadows - Layer Shadows will output shadows of objects with a layer ID greater than 1.