How to create line feature by tracing using ArcObjects?

Discussion created by huangs3 on Jul 9, 2012
Hi Everybody:

    In ArcMap 10, if I start editing to create line features, I can use the "Trace" tool to create it along an existing line feature. Now I want to automate this process: the begin point and end point are known on an existing line feature, create a new line feature which is a segment of the existing line feature between the two known points.
    From where shall I start? any hints such as interface name will be welcome.
    Thank you!