An imported datum curve can consist of one or more segments. Multiple segments are not necessarily connected.
The From File option imports a datum curve from a Pro/ENGINEER .ibl, IGES, SET, or VDA file. Pro/ENGINEER does not automatically combine the curves imported using From File into a composite curve.
Pro/ENGINEER reads all the curves from an IGES or SET file, then converts them to spline curves. When you import a VDA
file, the system reads the VDA spline entities only.
The .ibl file format is very much like that of a blend file, except you should precede the coordinates of each segment of the curve with both begin section and begin curve. Two points in a section define a line, while more than two define a spline.
To connect curve segments, make sure the coordinates of the first point are the same as the last point in the previous
You can redefine datum curves that are created from a file and you can trim or split them with other curves that are imported from a file.
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Example: Sample Datum Curve File
A simple example using arclength blending is given in the help.