The Interactive Standard Base node accepts inputs for different types of maps.
All surface points that are less opaque than specified are considered non-existent. For example, a value of 0.05 removes all surface points with a transparency of 99.5% or more.
The metallic map is a mask that determines the areas of the object that are metallic and the areas that are not. Values in the map should be 0 or 1, with non-metals as 0 and metals as 1. The map value should represent the top layer of the material; therefore, painted metal should not be set to 1 as paint is not a metal.
The roughness map determines how rough a surface is, and thus its reflectivity. A roughness of 0 represents a smooth surface and thus perfect reflection. As you increase the roughness value, the reflection becomes more scattered and more blurry.