What is the sequence of events fired when a page is saved.

Firstly, its SaveEdit

followed by SavePreChange

and finally SavepostChange

The SaveEdit event is initiated whenever a user attempts to save the
component. You can use SaveEdit PeopleCode to validate the consistency of data
in component fields. Whenever a validation involves more than one component
field, you should use SaveEdit PeopleCode. If a validation involves only one
page field, use FieldEdit PeopleCode.