What limits are in place when adding different thread types to an incident?

Environment:

Incident Workspace, All supported versions

Resolution:

When an agent is adding threads to an incident there are three types that can be added: customer entry, response, and private notes.  In the case of customer entry and response type threads, the product will only allow one uncommitted thread of each type at a time.  If the incident has an uncommitted thread of this type, the button to add a second will be greyed out.  However, once the thread is committed, the buttons will again be selectable. 

Private note type threads are not limited in this fashion.  Agents will be able to add multiple uncommitted private note threads at a time.