Has anyone got a lisp program to match all properties of a selected polyline to that of a target polyline,such that, say an polyline arrow can be matched to another arrow of a dfferent length/shape etc.Kind RegardsSyd

If you're talking about an arrow that's made with a Polyline having a first segment that's zero width at the tip and wider at the other end, then a "shaft" that's narrower than the wide part of the head, I imagine that could be done, but it would be complicated.  You'd need to dig out the width entries for each vertex and substitute them into the right places in the target Polyline.  And if the arrowhead length is not the same, you'd need to move the second vertex of the target Polyline.  I'm not sure I'm ready to think about what to do if the Polylines don't have the same number of vertices, unless you're talking about matching only width and length characteristics of the first segment, even if there may be different numbers of "shaft" segments that could otherwise remain as they are.
 
In the case of the same number of vertices and general configuration apart from differences in arrowhead length/width, consider a routine that I think would be much easier to create:  one that would Copy the source Polyline arrow to the position and orientation of the target Polyline, and Erase the target Polyline.
 
A drawing or image showing what kind(s) of matching you would want to do would be helpful.

Hello Kent
Many thanks for considering my problem again.
The objective of the routine would be basically to match properties of
simple arrowheads created from polylines; so other considerations which
you so rightly have outlined, however, need not apply in this case.
Moreover, I do like your second method as a solution which will achieve the same thing,
and indeed would probably include for a greater variety of polyline shapes,
without interrogating all the properties.
Kind Regards
Syd