ICU

ICU is a library for manipulating Unicode data. Xerces can use it to replace the platform specific "transcoder" that it would normally use to handle character set conversion. This is optional, except on Macintosh OS X because of a bug in Apple's support of the Macintosh "CoreFramework" APIs, which Xerces uses in place of ICU. To use Shibboleth on the Macintosh, Xerces MUST be built with ICU instead.

Project website: http://www.icu-project.org/

Non-Windows

If you're building from source on a non-Windows platform, a typically usable configure command would be:

./configure

Many different options are supported to enable/disable advanced features. Most are irrelevant to Shibboleth, but a few may add obscure capabilities that might be useful to some people.

Windows

Haven't tried it.