(INQ 10) or (INQ 15) for linewidth

[Lim Chee Beng]

Does (INQ 10) or (INQ 15) indicate the linewidth of a selected element? In help file, it says (INQ 15) is "element line size (alternate value to element pensize)", and (INQ 10) is just opposite of (INQ 15). It is confusing. What is the difference between them?
I found that I messed up between linewidth and linesize, pen size and line size. When should we use linewidth or another? What is the difference in drawing and plotting? Can somebody enlighten?

[Wolfgang]

the difference is the behavior when scaling parts.

one is scale independent, the other not.

Don't ask me which is which.. I'm mixing them up nearly every time. :D

[John Scheffel]

I think that linewidth shows on the screen and scales, but penwidth does neither of these. I also think linewidth doesn't affect plotting unless you use true color, but it has been a long time since I messed with it. Not sure if or when penwidth affects plotting or how it interacts with the plot transformation settings. If no one from CoCreate can provide a definitive answer, the only way to figure it out is to run some experiments.