With Knowledge Advanced, why are 'Notification Template Legend Keyword Substitutions' Notification-Type dependent?
Knowledge Advanced for Oracle Service Cloud (OSvC)
Notification Template Legend Keyword Substitutions are by-design Notification-Type dependent. For example, not all the Authoring Template Legend Keyword Substitutions are applicable to all Notification templates. When you edit an Authoring Notification Template, the Template Legend Keyword Substitutions list on the right column will show you which keyword substitutions are applicable for this current Notification Template.
To help illustrate, the <COM> and <WC> are not applicable in Content Subscription email template because they are typically used in the Task related Notification templates like "Workflow Task", "Translation Task", "Workflow Progress", etc.. Content Subscription emails are mostly for external OSvC-side Contacts (a.k.a. KnowledgeAdvanced-side Web users). So, it makes business sense (in respect to security concern) not to expose the <COM> and <WC> information (which mostly for internal OSvC-side Accounts, aka KnowledgeAdvanced-side Console users) via Content Subscription emails then.
While the <COM> and <WC> information are mostly for internal OSvC-side Accounts, a.k.a. KnowledgeAdvanced-side Console users. For this reason, these are not available via Content Subscription emails.
In the event an unsupported (not applicable) keyword substitutions is added to a given Notification Template (say <COM> in Content Subscription email template as example above), the template will still work, but with null/empty value(s) assigned to the unsupported (not applicable) keyword substitutions.