This standard specifies a method for determining the softening point of phenolic resins specifically designed for digital printing materials using a micro melting point apparatus. The method is applicable to thermoplastic phenolic resins synthesized from alkylphenols and formaldehyde, which exhibit a flat fracture surface. The principle involves directly observing the temperature at which the sample undergoes morphological changes (such as edge rounding or height reduction) under heating using an optical microscope. The core testing instrument specified in the standard is the micro melting point apparatus, a device that combines precise optical microscopy with high-precision programmable temperature control, enabling clear and continuous monitoring of the physical changes in the sample during the heating process.