Double-marking language

Double-marking language is when we use two different marks or symbols to represent the same sound or word in written language. It's like having two names for the same thing or person.

For example, in English, we use the letter "C" to represent the "k" sound and also the "ch" sound (as in "cat" and "church"). In some languages, like Spanish, certain letters always make the same sounds, so there is no need for double-marking.

However, in languages like Mandarin Chinese, which has four different tones that can change the meaning of a word, double-marking is necessary. They use a symbol called a "pinyin" to represent the sound and a tone mark to indicate the tone.

So, double-marking can help make written language more precise and clear, especially in languages where the same sound could have different meanings depending on the context.