Please answer a question about the following article about Russian language:

Because of many technical restrictions in computing and also because of the unavailability of Cyrillic keyboards abroad, Russian is often transliterated using the Latin alphabet. For example, мороз ('frost') is transliterated moroz, and мышь ('mouse'), mysh or myš'. Once commonly used by the majority of those living outside Russia, transliteration is being used less frequently by Russian-speaking typists in favor of the extension of Unicode character encoding, which fully incorporates the Russian alphabet. Free programs leveraging this Unicode extension are available which allow users to type Russian characters, even on Western 'QWERTY' keyboards.

What does 'mysh' mean?
mouse