In <a href="https://www.unicode.org/versions/Unicode8.0.0/">The Unicode Standard 8.0</a>,
Section 4.5 "General Category" defines a set of character categories.
Go treats all characters in any of the Letter categories Lu, Ll, Lt, Lm, or Lo
as Unicode letters, and those in the Number category Nd as Unicode digits.
</p>

<h3 id="Letters_and_digits">Letters and digits</h3>

<p>

pkg unicode, type CaseRange struct, Lo uint32
pkg unicode, type Range16 struct
pkg unicode, type Range16 struct, Hi uint16
pkg unicode, type Range16 struct, Lo uint16
pkg unicode, type Range16 struct, Stride uint16
pkg unicode, type Range32 struct
pkg unicode, type Range32 struct, Hi uint32
pkg unicode, type Range32 struct, Lo uint32
pkg unicode, type Range32 struct, Stride uint32