Abs Vector produces absolute values across the X, Y and Z components, effectively making each a positive number by negating the negative values.
This example uses a colour/vector source that produces positive and negative values in the three X,Y,Z directions. Vectors may have values greater or lower than the visible range of 0 to 1, hence the black areas in the top preview panel. This pattern is then used as a vector displacement map which in turn displaces a Plane Object to show displacement in three directions.
Abs_Vector_01.jpg
When we insert an Abs Vector node, all negative values become positive.
Abs_Vector_02.jpg
If there's any errors, omissions or questions about the above, please leave a comment and we will add further details in this post when relevant.
https://planetside.co.uk/wiki/index.php?title=Abs_Vector