The format of trademark registration numbers varies from country to country or region, and different trademark registration agencies may adopt different formats and naming rules. The following are some common trademark registration number formats:

1. Numeric format: Trademark registration numbers can consist of pure numbers, such as 12345678.

2. Letter + number format: The trademark registration number can be composed of a combination of letters and numbers, such as A123456.

3. Year + number format: The trademark registration number may contain year information, followed by a number sequence. For example, 2021-123456.

4. Number + classification symbol format: The trademark registration number can be composed of a combination of number and classification symbol, which is used to indicate the category of goods or services to which the trademark belongs. For example, TM1234567-01, where "TM" represents the trademark, "1234567" is the serial number, and "-01" represents the classification symbol of the goods or services.

Please note that the above are just some common examples of trademark registration number formats. The actual trademark registration number format may vary depending on countries, regions and trademark registration agencies. Trademark registration numbers are usually assigned by the trademark registration agency according to its internal naming rules and systems.

If you need to query or understand the format of a specific trademark registration number, it is recommended to consult the local trademark registration agency or a professional trademark agency, who can provide more accurate and specific information.

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