E.g.

for the default action:
prefix/<some configurable string>/item-alias
which should then NOT add the returnID in the the url, even when no custom url
is defined. It can use the default summary page if defined in preferences

for the category action:
prefix/<some configurable string>/cat_alias
prefix/item-alias/ 
which should then NOT add the returnID in the the url, even when no custom url
is defined. It can use the default summary page if defined in preferences