First of all, the accuracy of the query cannot be absolutely guaranteed. No country or institution can guarantee the absolute accuracy of the inquiry. The main reason for this situation is that the inquired files are not complete and accurate, and the inquirers are not accurate in grasping the approximate official review scale. They don't report trademarks that should be regarded as similar as not similar, but they should not judge similarity as similar.

Two, from the query scope, some countries can only query text and digital trademarks, not graphic trademarks. Relatively speaking, the query of word mark and numbers is relatively simple, while the query of graphic trademarks is relatively heavy and difficult, which makes some countries not accept the query of graphic trademarks. Therefore, in these countries, people can't get pre-registered or applied graphic trademarks through pre-application inquiry, so they can't know whether they will encounter obstacles in the application process.

Third, it will take some time to find the newly submitted application. New applications usually have to wait several weeks to get official receipts. Information such as application date, application number, trademark pattern, commodity, applicant's name and address can only be entered into the computer database or recorded in the trademark literature library after the official receipt is issued. Therefore, there will be some applications that have not been submitted for a long time and cannot be queried. This part of the application that the searcher wants to submit may have obstacles.

Fourth, the priority of application may constitute an obstacle to the inquiry after the application is submitted. According to the Paris Convention, an applicant from any member country of the Paris Convention can claim priority when submitting an application for the registration of the same trademark to another member country within six months after submitting an application for trademark registration to one member country, that is, the date of the first application is the application date. Therefore, some trademark applications can get an earlier application period by claiming priority, which may constitute an obstacle to the trademark application with the actual application date ahead of schedule. Because of the unpredictability of this situation, trademark inquiry is powerless.

Fifth, it is difficult to identify cross-class approximate trademarks. Most countries inquire according to the classification of goods and services, but the international classification of goods and services registered by trademarks is similar to that of some other countries or regions. For example, in the similar commodity classification table used by the Trademark Office of the State Administration for Industry and Commerce of China, it is clearly pointed out that the cosmetic utensils in Class 2 1 of the international classification table are similar to those in Class 3, and the welding equipment in Class 9 is similar to that in Class 7.

There are also some commodities that are not classified as cross-class approximation in the commodity classification table, but according to the nature and use of the commodities, they may be identified by the examiner as similar to another kind of commodities. For example, the trademark application for "spark plug" using category 7 goods was ruled to be similar to another registered trademark of category 12 "spark plug for automobile" after objection. For this kind of goods, it is not enough to search only on one kind of goods. Only by relying on the advice of professionals with rich knowledge of commodity classification can we try our best to avoid omitting trademark registration or application that may constitute obstacles.

6. Well-known trademarks that may constitute obstacles are not within the scope of inquiry. According to the provisions of the Paris Convention, unregistered well-known trademarks should be protected, and whether a trademark is well-known or not should be judged by the trademark authorities or courts of various countries according to the specific circumstances. Therefore, if an unregistered trademark that cannot be found through trademark examination is recognized as a well-known trademark and enjoys protection according to the Paris Convention, it may pose an obstacle to similar trademarks. Also, the protection of well-known trademarks is often not limited to its registered categories and commodities, which must be understood before trademark inquiry. For example, the trademark of a beverage production enterprise is not registered on "clothing", but because it is recognized as a well-known trademark, the same trademark registered by another enterprise on clothing is revoked according to law.