How to use RFACE parameter in STAAD.Pro

In SP-16, Design charts for combined axial compression and bending are given in the form of interaction diagrams in which curves for P_u/f_ckbD versus M_u/f_ckbD² are plotted for different values of p/f_ck, where p is the reinforcement percentage.
Charts for rectangular sections have been given for reinforcement equally distributed on two sides (charts 27 to 38) & for reinforcement equally distributed on four sides (charts 39 to 50). 

In STAAD.Pro, during design of a concrete column member using IS456 code, user can specify the face of the column for longitudinal bar arrangement using the RFACE parameter. There are three options provided. 

1.  RFACE 2 - 2 Faced distribution about major axis, i.e. reinforcement shall be placed along the 2 edges parallel to local Z axis
   
2. RFACE 3 - 2 Faced distribution about minor axis, i.e. reinforcement shall be placed along the 2 edges parallel to local Y axis
   
3.  RFACE 4 - Longitudinal reinforcement in column along 4 faces, i.e. reinforcement shall be placed on four sides

The default value is 4 which indicates that program will arrange the longitudinal reinforcement bars equally at four faces of the column. 
Now, let us under stand the local Y and Z axis of member.  In the property dialogue box, YD is depth and ZD is width of member as per property window. Let us see the isometric view of member with local axis.