What is the symbol for long o and short o?

There is no universally accepted symbol for long o and short o. However, there are a few common ways to represent them:

Long o:

* ō (macron over the vowel)

* oː (colon after the vowel)

Short o:

* ŏ (breve over the vowel)

* o (no special mark)

The specific symbols used will depend on the context, such as the language being studied or the specific phonetic system being used. For example, in some phonetics textbooks, the symbol for the short o sound might be written as /ɒ/.

It's important to note that these are just conventions and not hard rules. The most important thing is to be clear about what you mean when you are using these symbols.