In the info document for 'grep', in the section:
3.2 Character Classes and Bracket Expressions
I am curious on what the following bracket expressions are used for - I played with them to try and find out on my own, but was not successful:
represents the open collating symbol.
represents the close collating symbol.
represents the open equivalence class.
represents the close equivalence class.
I am well acquainted with the other bracket expressions, respectfully.