A new FAQ page devoted
to the topic of private-use characters, noncharacters, and sentinels has been
posted on the Unicode web site. This FAQ aims to clear up confusion about
whether noncharacters are permitted in Unicode text, and how they differ from
ordinary private-use characters. The recently published
Corrigendum #9:
Clarification About Noncharacters makes it clear that noncharacters are
permitted even in interchange, and the new FAQ page addresses some of the fine
points about their usage and about differences from other types of Unicode code
points. The brief mentions of noncharacters in other FAQ pages have also been
updated accordingly.
Are you unclear about what Unicode “noncharacters” even are? The new FAQ page
also answers basic questions about noncharacters and private-use characters, and
provides a bit of history about how they came to be part of the Unicode
Standard.