The boundary characters ^ and $ are very important. In fact, there might be no other way to specify start and end of input or line. Note that the operation mode for these boundary operators are important, as they might operate either on the full buffer or on just the last line.

The regular expression library is still lacking in some ways compared to the implementation in JDK 1.4 (or Perl 5). The library should be extended to support as many constructs as possible. In particular the missing features are specific character sets, and some boundary constructs (as ^ and $).