property Edit.LockedLine(Index as Long) as Boolean
Specifies whether a line is locked or unlocked.

TypeDescription
Index as Long A long expression that indicates the index of line being locked or unlocked. 1 means the first line, in the text, 2, indicates the second line in the text and so on. 
Boolean A boolean expression that indicates whether the line is locked or unlocked. 
Use the LockedLine property to lock or unlock a line. A locked line can't be edited. Use the Locked property to lock the entire control. A locked control is read-only. Use the BackColorLockedLine or ForeColorLockedLine property to specify the background and foreground colors for locked lines. Use the ForeColor property to specify the foreground color for a specific line. Use the BackColorLine property to specify the background color for a locked line.