All built-in functions taking char parameters have been overloaded to accept unichar as well. Built-in functions with more than one parameter, when called with at least one unichar parameter, results in implicit conversion of any non-unichar parameters to unichar.
To guarantee the integrity of surrogate pairs when enable surrogate processing is set to 1 (the default), the string functions do not allow surrogate pairs to be split. Positions are modified to fall at the beginning of a surrogate pair.
Several new built-in functions have been added to round out the unichar support. Included are the functions to_unichar() and uscalar(), which are analogous to char() and ascii(). The functions uhighsurr() and ulowsurr() allow the explicit handling of surrogate pairs in user code.
