Using parameters is best practices if you want to transfer data to other forms, but there are no rules you have to follow. In cases where want to retrieve and show data from a SMO, you can use data labels.

Thank you Prineel,

You mean that i can transfer data to other forms using either parameters or data labels

but as a best practice i should use parameters, right?

Hi

To pass values between forms it is best practise to pass them using a query string parameter. It is also recommended to pass this parameter as a GUID. Then on the rule “when a server loads the form” you can retrieve that parameter and load data from your data store so that when the form is presented to the user that the data is already present. There are some caveats to what should and shouldn't be loaded on the server side vs client side. 

https://help.nintex.com/en-US/nintexautomation/UserGuide/current/Content/Create/K2Designer/Rules/ServerRules.htm

If the value that you are passing between forms needs to be displayed on the form, then when the form loads you can populate the label on the form with the value from the query string. Fruther more you can then have a rule “on changed” of that label that would execute additional logic should you need to.