There's an usual issue about the domain names.There are many domain names with different suffixes. So if others register some names only with different suffixes, your clients may confuse when they search your site. But everyone has the rights to register the unregistered names. So he could register the domain names which are similar to yours. But they have different suffixes.
You'd better apply to register other names with different suffix but identical domain name firstly. www.JE-Net.org.cn is the company of dealing with domain name disputes and domain name registration centre which is authorized by CNNIC. You can require on it: www.JE-Net.org.cn
Or contact: info@JE-Net.org.cn