Link Interface

Apologies, 
I'm not following the use case.  Can you clarify?

Example, I have one Interface, and would like to make a link to another interface. The only way I see now is to make a report which will opens the other interface and than to use a!reportLink() function to open this report which will open the other interface. 

It is basically a link between two interfaces. 

Appian typically displays interface rules in one of three ways; a record view, a report, or a user input task.

What's your use case?

I would to display a record type but all the results inside the record not a single one. And they to show in the same window not in a pop-up. 

Do you have to link externally? What if you create a link that shows more details inline on the current interface?

You can have a dynamic link which could show or hide a section in your form with more details. Here's an example from the documentation on how to configure a grid that can show more details if you select a row.

I think it would also be helpful to describe your use case more from what experience you want the user to have so we can suggest the right procedure. For example, suppose I have a manager who receives a task to approve a purchase request. They also want to see the details of each item requested without linking to another page. In this example, I'd suggest creating a dynamic link somewhere on the form that can show / hide a section with the details of your items.

Hello Peter, 

The link is internal.  Imagine how in the top menu where are the 5 principal buttons I can link them to Interface. The same way I would like to be able to link One Interface to another. Interface One have a button when I press it then to open another interface. 

Did you try the dynamic link? I still think that is the best way to approach this use case if you don't want a report link. Here's another example of how that could work:

a!localVariables(
  local!currentInterface: 1,
  {
    a!linkField(
      links: a!dynamicLink(
        label: "Link to Interface 2",
        value: 2,
        saveInto: local!currentInterface
      )
    ),
    choose(
      local!currentInterface,
      
      /* Replace this with your initial interface */
      a!sectionLayout(
        label: "Interface 1"
      ),
      
      /* Replace this with the interface you want to link to */
      a!sectionLayout(
        label: "Interface 2"
      )
    )
  }
)

Did you try the dynamic link? I still think that is the best way to approach this use case if you don't want a report link. Here's another example of how that could work:

a!localVariables(
  local!currentInterface: 1,
  {
    a!linkField(
      links: a!dynamicLink(
        label: "Link to Interface 2",
        value: 2,
        saveInto: local!currentInterface
      )
    ),
    choose(
      local!currentInterface,
      
      /* Replace this with your initial interface */
      a!sectionLayout(
        label: "Interface 1"
      ),
      
      /* Replace this with the interface you want to link to */
      a!sectionLayout(
        label: "Interface 2"
      )
    )
  }
)