Abstract: An approach is presented to search profile in engineering drawing based on the turn-to-the-left-most rule.It is called expanded turn-to-the-left-most rule.A term named guiding-line is brought forward for the expanded rule.It could solve the incompletion in searching profile by the quondam rule.Owing to the guide-lines,all the profiles could be found,including those which couldn’t be found through the turn-to-the-left-most rule using the same first profile line.An instance is given to compare the...

Key words: the-turn-to-the-left-most-rule； profile； guide-line； 2D to 3D；