In the Issues list there are Issue ID values that show up in the
views and it says they are "(linked to item)". Sharepoint assigns a
value to it. Where does it get this value? Is the value only used in
the list or is it used throughout the site, the site collection or
the content database? It is not always consecutive.

Also, can you create an incremental field, ie it starts at 1 and
automically increments with each new item added to a list?