This section describes the built-in datatype 'token' derived from 'normalizedString'. Whitespace characters are collapsed to a single ' ' character. Leading and trailing whitespace characters are removed.
The next "string" derived dataype we are going to look is: "token".
"token" is a datatype derived from "normalizedString" datatype
by collapsing whitespace characters to space characters
and removing leading/trailing space characters.
"token" value set is smaller than "normalizedString" value set.
It contains only unique "normalizedString" values after
consecutive whitespace characters of '\t', '\r', '\n' and ' '
are collapsed to a single ' '; and leading and/or trailing ' ' are removed.
Note that repeating whitespace characters are still allowed in "token" lexical representations.
But they are replaced by a single ' ' to obtain "token" values.
For example, 5 XML elements below are all valid and represent the same "normalizedString" value: