What are the types of triggers and how the sequence of firing in text item?

Answer:

Triggers can be classified as Key Triggers, Mouse Triggers ,Navigational Triggers.
Key Triggers :: Key Triggers are fired as a result of Key action.e.g :: Key-next-field, Key-up,Key-Down
Mouse Triggers :: Mouse Triggers are fired as a result of the mouse navigation.e.g. When-mouse-button-presed,when-mouse-doubleclicked,etc
Navigational Triggers :: These Triggers are fired as a result of Navigation. E.g : Post-Text-item,Pre-text-item.
We also have event triggers like when ?Vnew-form-instance and when-new-block-instance.
We cannot call restricted procedures like go_to(??my_block.first_item??) in the Navigational triggers
But can use them in the Key-next-item.
The Difference between Key-next and Post-Text is an very important question. The key-next is fired as a result of the key action while the post text is fired as a result of the mouse movement. Key next will not fire unless there is a key event.
The sequence of firing in a text item are as follows ::
a) pre - text
b) when new item
c) key-next
d) when validate
e) post text