Names can start with letters including non-Latin characters.
Names can start with dash (-) character.
Names cannot start with numbers or other punctuation characters.
After the first character, numbers, hyphens, and periods are allowed.
Names can't contain spaces.
Names can't contain the colon (:) character.
Names can't start with the letters xml, in uppercase, lowercase, or mixed.
There can't be a space after the opening <
There can be space before the closing > character.
Here are some examples of valid names: <first.name>
Following are some examples of invalid names:
<xml-element> which starts with xml,
<123> which starts with a number,
<your=xml> because the equals sign (=)sign is illegal, and
<your element> which contains a space.