This module is about the string part of plain Perl scalars. A scalar has a
string value, which is notionally a sequence of Unicode codepoints, but may be
internally encoded in either ISO-8859-1 or UTF-8. In places, and more so in
older versions of Perl, the internal encoding shows through. To fully understand
Perl strings it is necessary to understand these implementation details.

This module provides functions to classify a string by encoding and to encode a
string in a desired way.

This module is implemented in XS, with a pure Perl backup version for systems
that can't handle XS.