SYSTEM.CURSOR_BLOCK in Oracle Forms

SYSTEM.CURSOR_BLOCK:-
 
The value that the SYSTEM.CURSOR_BLOCK system variable represents depends on the current navigation unit:

• If the current navigation unit is the block, record, or item (as in the Pre- and Post- Item, Record, and Block triggers), the value of SYSTEM.CURSOR_BLOCK is the name of the block where the cursor is located. 

• The value is always a character string.

• If the current navigation unit is the form (as in the Pre- and Post-Form triggers), the value of SYSTEM.CURSOR_BLOCK is NULL.