Likewise, conformant implementations of ISO/IEC 10646 [2] may support subsets rather than all characters in ISO/IEC 10646.

But ISO/IEC 10646 goes much further than Unicode. A subset is defined as either an implementation-defined list of code points, a standardized collection, or a combination of the two. Collections are standardized in Annex A of ISO/IEC 10646.

In the following subsections, we study collections in Annex A. But it is interesting to note that ISO/IEC 10646 does not provide a standard notation for specifying subsets. Different collections in Annex A are represented by different notations.