I found it in my company's OM-A as "Occurrence Reporting List". The official reference is: EU 2003/42/EC, ANNEX I
Now superseded by...
reg 376/2014.
Note that accidents and serious incidents are covered by different legislation - I forget the reference right now - but the things in 376 and the other reg are not mutually exclusive, so you might hove to comply with both regulations for the same event.