Using L1, L2 and L3 OR 3-phase symmetric is allowed but not both. Document this exclusivity.

[lfse-slafleur]

From Discord:

Dolf Andringa — 11/3/2025 4:48 PM Hi @Ewoud Werkman @Wilco Wijbrandi @Jorrit Nutma : The POWER.3_PHASE_SYMMETRIC commodity type is not enforced mutually exclusive with POWER.L1,POWER.L2,POWER.L3. Is this intentional? It seems that specifying both at the same time can cause confusion. 
Jorrit Nutma — 11/3/2025 5:47 PM Valid point. I think we should add that mutual exclusivity, at least in the open source documentation.
Ewoud Werkman — 11/3/2025 5:55 PM And in the next edition of the standard.