Specifications that limit the length of a string SHOULD require truncation on grapheme boundaries, as truncation in the midst of a combining or joining sequence can alter the meaning of the string.
+Specifications that limit the length of a string SHOULD require truncation on grapheme boundaries, as truncation in the midst of a grapheme or combining character sequence can alter the meaning of the string.
When specifying a length limitation in code units (such as bytes), specifications SHOULD set the maximum length in a way that accommodates users whose language requires multibyte code unit sequences.
+When specifying a length limitation in code units (such as bytes), specifications SHOULD set the limit in a way that accommodates users whose language requires multibyte code unit sequences.
If a specification specifies a length limit in code units (such as bytes), it MUST specify the character encoding used in measuring the limit; such a limit SHOULD NOT specify a legacy character encoding.
+If a specification permits or requires truncation of a field, the character encoding is important in knowing what the limit means. If the limit is in bytes and legacy character encodings are permitted, note that conversion of Unicode data to a non-Unicode encoding can also result in data loss (since most legacy character encodings encode only a subset of Unicode).