What does it mean to take part in a calligraphy competition and write that no self-made words are allowed?

In the calligraphy competition, "no self-made characters" means that participants can't use their own words in their written works. Calligraphy works require the use of standardized Chinese characters, that is, words that have been formally included in dictionaries such as Modern Chinese Dictionary and Kangxi Dictionary. Self-made characters refer to characters that are not recognized and widely used, and do not conform to the writing norms and traditional fonts. The purpose of the competition is to promote the inheritance and development of traditional culture, so participants are required to use standardized glyphs in their calligraphy works.