title: What is the difference between declaring a package and importing a package in a Modelica model?
body: <p>I could declare a package or import a package in Modelica models, but I am not sure if there is any difference between them, I tried the following code, both of them work fine.
  My question is :
  Is there anything I should pay attention to when using these two methods?</p>
  
  <pre><code>partial model A
    package SI1=Modelica.SIunits;
    import SI2=Modelica.SIunits;
    SI1.Voltage u1;
    SI2.Voltage u2;
  end A;
  
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/Hj4xu.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Hj4xu.png" alt="enter image description here"></a></p>