Low Description
Cassandra allows keyspace names to start with a digit or an underscore (see o.a.c.db.migration.Migration.isLegalName), but CQL's USE statement only accepts a CQL identifier, which must start with a letter. So there's no way to use a keyspace named "142" or "_hi_" in CQL, for example.
The USE statement should accept string literals and integers as well as identifiers, and CQL identifiers (IDENT) should probably allow starting with the underscore.