Question about combinatorial extension

[Rich Piazza <rpiazza@mitre.org>]

Hi Alan,

 

I didnât want to belabor the point on the call yesterday, but I wanted to check my understanding of the combinatorial extension.

 

Letâs assume that we have two extensions defined (similar to the spec examples):

I introduced new ids, so as not to confuse it with other extension examples.

 

{

  âidâ: âstix-extension--9994a318-2a81-4b04-a79a-7c515cfae643â,

  "type": "stix-extension",

  âspec_versionâ: â2.1â,

  "name": "Extension My Favorite SDO",

  "description": "This schema adds a new object my-favorite-sdo",

  "created_by": "identity--uuid1",

  "schema": "https://www.example.com/schema-my-favorite-sdo/v1/",

  "version": "1.2.1",

  âextension_typesâ: [ ânew_sdoâ ]

}

 

and

 

{

  âidâ: âstix-extension--29c8ae7a-6779-40dd-92e5-0806cb61a6faâ,

  "type": "stix-extension",

  âspec_versionâ: â2.1â,

  "name": "Extension Foo",

  "description": "This schema adds rank and toxicityâ

  "created_by": "identity--uuid1",

  "schema": "https://www.example.com/schema-foo/v1/",

  "version": "1.2.1",

  âextension_typesâ: [ âextends_subcompâ ]

}

 

Using these extensions, Iâm not sure what would change in your instance on page 221, except the indicator would be using the extension stix-extension--29c8ae7a-6779-40dd-92e5-0806cb61a6fa instead of the combinatorial extension that included both extension types (stix-extension--a932fcc6-e032-176c-126f-cb970a5a1fff).

 

So what is the advantage of the combinatorial extension?  What am I missing?

 

                Rich