This feature is currently still experimental, and need to be activated in Octane Preferences / Trouble Shooting / 'Activate Value Texmaps [Experimental]'
(Once activated, 3dsMax needs to be restarted)
This is supported for all Octane materials and textures, and allow to use a common value to control several different textures or materials.
Many parameters, like the Opacity of materials can already be set as a Texture, and be shared by multiple materials.
Some other values, like Bump height or Film IOR used to be internal to each material / textures.
Those values can now be set as Texture and shared by multiple textures.
In the material editor, a square button is available on the right side of compatible parameters. Click or drag to set a Value texmap.
As with other 3dsMax texture buttons, use the context menu (right click) to Clear, Copy, etc..
Another example: the Flake size of a Flake texture can be set as a Float value texture, and the Thickness 1 of a Stripes texture can be set to the same Float value texture.
Changing the value of the Float value texture will affect both the Flake and the Stripes texture.
Each type has a set of compatible textures, that can be combined, using Operators, Converters, Utility.
Using a multiply operator can also help to manipulate some parameters more easily.
For example, if you need to adjust the Bump height in the range 0.001 and 0.1, use a Binary math operator with the Operation set to Multiply and Argument B set to 0.0001, so you can control Argument A with values between 0.1 and 10.
That can help in some cases if the precision (number of digits) set in 3dsMax preferences is too low to edit small values.
This can also be used to bypass the default limits of a parameter.
The Octane value textures are also available for parameters of OSL textures.