Documentation for esriFieldTypeGlobalID and esriFieldTypeGUID

[MeganAlnico]

I'm calling https://developers.arcgis.com/rest/services-reference/online/add-to-definition-feature-service-.htm

to add fields to a layer. Is there any documentation for what esriFieldTypeGlobalID and esriFieldTypeGUID are used for? I'd like to use one for the UUID that we use as a unique identifier but am unsure which to choose. 

Also,  are fields like:  actualType, sqlType required? 

I did a google search but can't seem to find any explanation. 

[ChrisSeabrooke1]

Global IDs and GUIDs have a few differences. ArcGIS actively maintains Global ID fields (that is, when a new feature is created, a GUID value is assigned), whereas, GUID fields are left blank. ArcGIS will add a GlobalID field to a layer. You cannot edit the field, so if you need to edit the value, use a GUID type field. If you want ArcGIS to automatically enter the value, use the GlobalID field.  Hope this answers your question.

[MeganAlnico]

Thanks so much! That's perfect. Any idea about actualType and sqlType?

[ChrisSeabrooke1]

I don't use either actualType or sqlType. I've had failures when I tried to set the sqlType. I'm not 100% sure, but I think the sqlType  is set based on the backend (Enterprise systems might have different backend database systems).