They are described as follows:
1, t: indicates the TrueType font format (suffix is. ttf)。 TrueType is a new mathematical description technology jointly proposed by Apple and Microsoft. It uses mathematical functions to describe the outline of fonts, including font construction, color filling, digital description function, process condition control, grid processing control, additional prompt control and other instructions.
2.o: indicates that OpenType is also called Type 2 font (suffix is. otf)。 OpenType is another font format developed by Microsoft and Adobe. It is also an outline font, which is more powerful than TrueType. One of the most obvious advantages is that PostScript can be embedded in TrueType software.