Sometimes, in order to save the application fee, multiple inventions (utility models) with corresponding specific characteristics can be jointly applied. The premise of joint application belongs to a general concept of invention, that is, there should be oneness between exclusive rights. For the judgment of oneness, please refer to the judgment chapter of oneness in the review guide.
For a simple example, the characteristic of product A is B; The manufacturing method c is characterized by d
Here, product A and method C belong to an invention respectively. As two applications, they should have only one independent claim.
If C is specially used for A, and the characteristics of D are related to B, then A and C are unitary, belonging to the general inventive concept and can be applied together. The product independent claim of A and the method independent claim of C will appear in this application respectively.
I don't know if you can understand this, but the one upstairs is also correct. You can look at it together and understand it better!