1. Return or returnex only work if called from the basic event handler - if called from several nested aliases below it doesn't work.

2. Goto presumably only works inside an alias - so doesn't actually halt processing.

3. Calling an alias which requires a parameter I will try.

4. Invalid syntax stops the script but produces an error message.

The use case is a very large script which is structured as many small aliases which each do simply things - and to halt all script processing for an event which might need to be /haltdef but not on this occasion (and so has a ^ prefix) from within an alias several nested calls deep but on this occasion without doing a /haltdef.