The CUPM admin interface supports creation of Alias values with spaces in them. So I can have a alias value of Test 1
I also understand that Alias values need to be unique. I have tested this in the CUPM admin interface by trying to create two user records with the same alias name, but it will not allow me.
 
From CUPI, I can use the following query method to retreive the User object by alias.
 
Assuming a alias name of test. 
 
/vmrest/users?query=%28alias+is+test%29
 
This does return me a valid response and does return the User object.
 
If the alias has a space in it, thats when I get an error response. Going back to the example, lets try and query for the User with alias Test 1
 
/vmrest/users?query=%28alias+is+Test+1%29
 
This is the response that i get back :
      <ErrorDetails><errors><code>INVALID_PARAMETER</code><message>filter should have three parts: alias is Test 1, type=3</message></errors></ErrorDetails>
 
Any insight will be appreciated.