Direction in a PTCAR element is defined by the PTCDIRECTION keyword (minimum abbreviation PTCDIR), followed by the direction specified in terms of the X, Y, Z axes and rotations towards those axes. For example:

For other examples, see Figure 5:6.: Example of two Cartesian P-Points. Note that any one, any two, or all three of X, Y, Z may be present in the PTCDIR command line, in any order. The rotation value may be positive, negative or absent altogether (i.e. zero). If you do not define the direction, DIR Y is assumed.