The rest are discussed in Harry Roberts article from 2015 titled More transparent UI code with Namespaces specifically the namespaces section of the article.
For further actions, you may consider blocking this person and/or reporting abuse
We're a place where coders share, stay up-to-date and grow their careers.
The ".u - Utility" is part of SUITCSS naming conventions.
The rest are discussed in Harry Roberts article from 2015 titled More transparent UI code with Namespaces specifically the namespaces section of the article.