In fact, there are a number of scripts that have been added since Unicode 2.0. This slide lists additional scripts that are all in everyday use in the modern world, but that cannot be used in XML 1.0 for element or attribute names or for purposes such as the enumerated list shown earlier:

• Ethiopic (Ethiopia, Eritrea, Somalia)
• Sinhala (Sri Lanka)
• Myanmar (Myanmar)
• Khmer (Cambodia)
• Canadian Syllabics (Canada)
• Thaana (Maldives)
• Mongolian (Mongolia)

For the roughly 150 million people using these scripts around the world, the 'X' in XML is likely to look more like the 'X' in 'exclusion' than the 'X' in 'extensible'.

Indeed, many loose characters have also been added to scripts that were already included in Unicode 2.0. This can present an even more problematic situation than a missing script. In some cases the additions are commonly used by people writing text in Unicode, and it will not be clear to them what versions of Unicode support what characters. If a person using, say, an Indic script includes one of these characters in their XML, it will be extremely difficult for them to work out why the XML doesn't validate.