My understanding is that bar and broken bar are remnants from the pre-digital era, when they were used to compose vertical lines, as also explained here:
In some typefaces bar and broken bar share the same height and depth, but in a great number of designs, they are not identical. I am wondering what the rationale for this difference is, whether it's just a legacy practice, or if there is a current use scenario that requires either same height or differing height. Or is it because the broken bar can appear to be taller than the bar when it aligns vertically with the bar?
Comments
For a while recently I was making them both long enough to ensure that with any normal line spacing, they will overlap from one line to the next. That way bar can provide a continuous line, and broken bar has one gap, in the middle of each line. But I gather that is not a common use case and there are other linedraw characters for that, so I am discontinuing that approach.
I wonder if perhaps some designers think "hey, we can make broken bar shorter, and have a gap between lines as well as in the middle." The problem with this theory is that the gap between lines is subject to the leading, and to different apps using different leading: auto-leading is either 20%, or based on WinAscent/WinDescent, or possibly font bounding box.
So, even without the user doing anything to line spacing, this will almost certainly make that inter-line gap inconsistent with the gap inside the broken bar, in at least some apps. I think that looks weird, so I don't do that.
I'd venture a guess that some current fonts are using Mark's logic of creating a dashed effect.
My opinion: make them the same height. Consider the box drawing glyphs for handling drawing vertically dashed lines. Of course, if you have a reason for choosing otherwise, do so.
Hopefully my memory is correct on those details. It's been close to 40 years since I used some of that gear. If you're interested in more of the historical details, I'd suggest looking at some of the early international standards on character sets and programming languages, perhaps PL/I. You might be able to find additional discussion references in old Usenet archives.
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) displayed as a broken bar. Anyone who grew up with the early *GA video cards will recognise the font instantly:Note that the solid bar on the 6th line is part of the line-drawing characters.
Following the introduction of ISO 9241-3, IBM introduced new fonts in PC DOS 5.02. The broken bar pipe character was replaced by one with a solid bar.
I would imagine the reason for having both bar and broken bar is to maintain that distinction.