The frame lines may be extended north, south, east or west at the top, bottom, and sides.  The below example shows a line extending east from the
bottom frame line.   The extensions are due to the re-cutting of the frame lines.  they are usually rather thin in appearance, like guide lines. The
re-cutting may have been done on the impression beofre it was placed in service and is therefore a fresh entry.  They may also be the result of
th imperfect removal of guide lines or from non-coinccidental re-entry.  These extended lines are very useful for plate identification because they
add in combination with other factors such as checkletter position, ray and other types of flaws (or their absence) to the inclusion or elimination
of possible plates.  They are usually very visable and easy to identify.