With the introduction of the Dynamic Case Management Framework, OutSystems advocates to use GUID as a unique Text Identifier (see https://success.outsystems.com/Documentation/Case_Management/Create_a_case_management_app).

Apart from that GUID as identifiers have some other use cases too:

• Less "hackable" URLs to your application pages than when using Integer Identifiers
• Less meaningful Identifiers (Employee number 2 is probably longer with the company than Employee number 58)
• You want the data to be uniquely-identified, no matter where it came from.
• You need to be able to combine data from difference sources with little-to-no chance of duplicate GUIDs.
• Furthermore, you don't want or don't care about the users needing to remember an ID themselves

It would be nice if there is more support in the Platform:

• Add a new datatype called GUID, with an AutoNumber option.
  
  
• Add a popup menu option to generate a GUID and set it as a string literal for any attribute of datatype GUID
  
  
• Add built-in feature to also generate a GUID for Mobile and Reactive, as it is currently only available server side. Yes Forge component exists to help you, but this should be build in.