The definition of SELV was defined in the IEC 60950 standard but it is not defined in the  IEC 62368 standard. This has been replaced with the ES1 Energy sources definition.
The definition of SELV is still applicable to the 61347-2-13 standard. In this standard it is that a LED driver will use a safety isolating transformer with double or reinforced insulation and the output voltage shall not exceed 120Vdc.
In the specification MEAN WELL’s 61347-2-13 certified LED drivers are marked with the SELV symbol in the case that the SELV requirements are fulfilled: