Ystok-URI is a part of YstokHTML collection but can be used alone. The code is based onRFC3986, (including userinfo).
URIs are represented by instances of a structure type. Percent-encoding/decoding is implemented in full. It is highly optimised for UTF-8 and supports other external formats basing on Lisp implementation-specific i18n/l10n functions or ACL-Compat.