From Willy: Define a standard for helper parts

[Eugen]

Hardcoding an offset would limit its usage to one side only - as soon as you rotated it by 180° it would vanish into the parts.

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For the case where helpers has text labels in specific script (i.e., left-to-right for Latin) there is only one side which could be used as front side on top of a referenced part.

But for all the possible cases Z-fighting in labels could be avoided just by duplicating labels in helpers files with offset "0.1 LDU" from origin on both sides — in such case at least one label (of two) would be always ontop of the parts' faces which would be coplanar with helpers' origins (another label would be inside the part).

Here is LeoCAD with duplicated "Helper 2D Ruler 100 LDU", offsetted from origin "0.1 LDU" and "-0.1 LDU" accordingly.