Note: Avoid spaces in the label name; otherwise, you will get an unexpected error when loading the file.
注意：标签名称中避免出现空格；否则，引导那个文件时会出现无法预期的错误。
2
If one of the invalid characters is in the label string, or the string is empty, the user is notified of the error and the label is returned to its previous text.
如果标签字符串中有一个无效字符，或者该字符串为空，则将向用户通知错误，同时标签返回到其以前的文本。
3
It unifies label and store position of the text in order to make it consistent in reading and writing and easy to check the error.