Sharp ZQ-2400 Operation Manual page 16

Cursor:
the next letter, number, or symbol will be entered. When correcting an
entry, move the cursor to the position where a character is to be typed
over or deleted. The cursor changes to " m ". When
the cursor changes to " 4 ".
18
Deletes the character at the cursor.
Deletes the character to the left of the cursor
("backspace").
Clears the data being entered.
The cursor is used to indicate the position where
inserting characters,