About the `ISYM` tag used for projecting the spin magnetization

I noticed the following description here:


Projecting the spin magnetisation requires the k-point mesh to cover the entire Brillouin zone. I.e., the DFT calculation must have been performed without symmetry (ISYM = - 1 in VASP).

But I also noticed the following descriptions/comments/notes:

  1. The official description given on vasp wiki about the ISYM tag:

For ISYM=-1 | 0, the use of symmetry is switched off.

As you can see, ISYM=-1 | 0 will switch off the symmetry. But the above-mentioned document of ifermi only says ISYM = - 1. Any hints for this setting?

  1. I’ve also noticed the following notice given by irvsp:

Do NOT set ISYM tag in INCAR.

Why do the two tools have opposite requirements for this option?